Initials-plus-hobby/interest/etc also seems common, particularly with sports.

In most places I either use my initials or else my first name, last name and baseball number from when I was a kid, all with no spaces. (eg. johnsmith87).

Or if I want more anonymity, I use a name I took off some random piece of hardware, which has absolutely no connection to me.

Fairlington for where I live and Blade for the team I support (Sheffield United - the Blades). It has a nice dashing, Zorroesque4 sound to it.

BB

It depends where I am. Here I am vague - other spots, my id more closely identifies me.

Former paleontologist, so I use dinosaur names. This one and others.

family name and a number that has deep significance to me! :)

For email (where people already know me to contact me), banks, brokerage, etc, it's first name initial, middle name initial, last name.

For things like this (where people don't know me nor should I care for them to know me), random names.

It's very difficult to attach anything I say online to the real me. No employer is going to find my writings by Googling my real name.

"wiredog" is a description of the job I had in the Army. I use that name at slashdot, here, and everywhere else I can. I even registered at DailyKos so that no one there could grab it.

It gives me anonymity online, without having to be "anonymous". And some people have met me in real life.

Well, my surname is even less common than yours (it didn't make the Census datafile that lists every surname with more than 100 entries) so getting the username I want has never been a problem. In the past when I don't want to reveal my identity, I go with something unrelated, but recently I've been trying to split the difference. Slar is, after all, a bastardization of my last name that my friends came up with and use as a nickname. If I'm doing music stuff, I go with Uke-Slar which is close enough to my actual name that even people who know me casually can probably figure it out. To me that is the best way to go - people who know me know this is me, but people who don't know me have no clear way to figure it out.

My main email address is first initial, middle initial, last name. Many places, I use a character name from a favorite book.

Before & during college, I went with "a made-up moniker that betrays to no relation to any of your real-world identifiers." Now that I've grown a little bit, I still choose something that can be associated with thousands of people but is still personal. No one can identify me based on that alone, but it still identifies a part of me. As a bonus it's easy to remember for those that do know and would like to contact me.

As with the other commentors, I use an id with my real name (first, middle, last) for business and other correspondence with friends and family. I use a vague first name + numbers for shopping and registering with websites. And, adopt various anonymous usernames where I don't see a reason to use any personally identifiable information, such as here.

Just recently I established a more whimsical moniker that I am in the process of securing rights to across a variety of email providers and websites and even going as far as registering the corresponding domain name.

I use the same thing, every time, and it clearly identifies me. I have an unusual surname and am an early-adopter so I have been able to get pretty much the same handle everywhere I've gone. The only exceptions were in the very early days of campus email at GW, when I got some odd unix-assigned monikers that are still google-able today and bring up my name.

If I have something to say that I wouldn't want associated with my real name, I don't say it. This is perhaps a radical concept in today's world, but it has worked pretty well for me.

I'm downright pedestrian about my username, going with my first initial plus the alpha characters of my last name - rodaniel. This is what I use almost everywhere.

That's my username at work so it's easy to remember. And my surname is uncommon enough that there's almost never anyone else already using that username - except on rare occasions when my brother Rich has beat me to it.

Name + location. I use it across the board whenever possible. It isn't esoteric but anonymous enough to keep anyone from being able to look me up in the phone book.

I use combos of favorite cars and motorcycles. I can add a year if I need to have numbers in the user name/password. Those that know me laugh when they see a post somewhere relating to Camaro, flathead, shovel, hemi, rocket 455. I am really annoyed when I set up access to a site and they have "standard" questions I must provide an answer for to get in. Questions like favorite movie or book...grrrrrrrrrrr. I have to write down the questions and my answers to remember. Life is short

I use the names of female characters in Bruce Springsteen songs. Usually Rosalita; sometimes Kitty or Wendy or the ever popular (with both Bruce and Internet commenters) Mary, combined if necessary with a sequence of numbers that has Bruce-related significance to me but possibly no one else.

College initials and first name.

I have a specific word that characterizes me and use different languages for the same word as needed or on occasion add a significant date. But in general I use the same two translations over and over. As a woman, I sometimes, use a fake male name in order to be taken seriously on certain boards. Sad but true even in 2008.

I have an online alter-ego that I have always used. Svejk, or combinations of Svejk with my year of birth or group affiliation has stood me well over the years. People know where/how to find me and people I don't know (or don't want to know) would never associate me with the name, which is taken from a literary character.

My surname is...well... hateful... thanks to the instability of the Current Occupant. That plus Potential Employer Googling has me use as my 'net-wide name a character from Welsh mythology. While few can pronounce it, it's only not been available once when I try to register someplace.

Damned Current Occupant.

I give away my political leanings, not my name.

I use the name of a favorite character in a book and add my birth year when needed. I've rarely had to improvise from there.

Initials and last name usually. When someone has beat me to it (and there is at least one well known mmrudy and a couple of relatives with the same moniker), I add my zip.

Id like something more imaginative, but probably wouldn't remember it!

I don't use my surname because it's very unusual; that means it will be available, but it also points directly to me, which is a personal security breach.

Heh. Thanks for the shoutout ;)

Totally dependent on context. For friends/general internet messing around, it's based off of a college nickname. For anything that I use in any work facet (Facebook, Twitter, etc.), it's name-based. I even have different email addresses and IM accounts to contact people in the different groups.

I provide support for an online network of web sites for insurance professionals.
In that capacity I am privy to their selected passwords. So as you might guess I see a wide verity if approaches to that requirement. Some are strong and secure and some are as weak as the use of the word "password". Some passwords are a window to the soul for instance 'kill4money" or "John3_16". I still have no insight to the agent that selected "colbycheese1967"

I once worked as a telemarketer selling tickets to a circus for a charity. Of course I wanted to use a phoney (no pun in ten did) name that was easily understood over the line. The office where the boiler room was, was over a store called Daniels Jewelers, so as I sat down the first day of work, I recalled the big sign on the front of the store, and used my fortunately simple given name with "Daniels" for the surname.

Most of the forums I visit are motorcycle related, so my username is the name of my first motorcycle. With my current email system, I can have several aliases, so for more professional type things, I give out FirstLast. (however, both my first and last names are frequently misspelled, so I still have to spell it out for people) All goes to the same email system, and it's smart enough so that when I respond to someone, it'll show the correct email name (either the bike or FirstLast, or others I have).

Its good to have the first/last name in the email address for professional use. The employer may not be interested in contacting a Machomanturtle@.. Vs john@..

I absolutely did not know I stumbled on the name of a supposedly well known children's book author until well after I've used the moniker in several places... which I got from well picking a point at random from a local atlas, and appending "North" when I found Sterling was taken. That said, I have created a elaborate fictional genesis for the name that makes me look much more clever than I am.

other than two family only email accounts with my real name, my user names are picked at random.