My first internet handle was Ronin (prefaced with a random adjective), which I used pretty much everywhere for several years. Netbattle is the first place where I used the handle kikuichimonji, and I signed up with that name at Smogon's birth. Around 2004, I started to try to ditch the handle Ronin, and tried replacing it with Artemis, Kuiper, or both. I quickly got rid of Artemis (due to gender confusion), although I've been forced to keep that name on Underground Gamer (and bitGamer), and inside that community, it's become almost synonymous with Suiseiseki and mudkips. Over the last several years, I've gradually been transitioning away from Ronin towards Kuiper, outside of the Pokemon community where I'll probably keep the name Kikuichimonji for the sake of recognition. (I sometimes use the nick "kikuman" or something like it on IRC, but I've never made a habit of it.) Several weeks ago, I finally asked Pojo to change my name from Fallen Ronin to Kuiper, and I've pretty much given up on all of my Ronin-related IM handles, although my main spam-catching email address does have "ronin" embedded in it.
Since Kuiper is an existing name, in large communities I often use a meaningful suffix, rather than numbers. I use kuiper_pkmn on Gamefaqs, and Kuiper RNG or Kuiper Desu for email and AIM. However, I'm not really an active participant in any truly massive only communities, so Kuiper works very well for the smaller communities I'm a part of. The only online game I play is Counter-Strike (and its Source counterpart), and in an environment where most communication is by mic, arguments often arise over pronunciation, so I usually use a handle like Desu. (I can only imagine what chaos might erupt if my handle were Suiseiseki.) Amazingly enough, I started using the name Desu on Counter-Strike Source before becoming a 4chan Party Van regular.
I've only had one YIM handle in my entire life, dullahan64. I could update it, but I have less than a dozen YIM contacts, only one of which I regularly converse with, and YIM allows you to chance the way names are echoed, so I'll probably never change.
I almost never namefag on chans, but when starting a thread, I usually use the name "opie" with a tripcode to avoid confusion, especially on /g/.
