irst of all, my real name is "neil", but these days, most people call me "fred". i won't go into the story behind that though... i used to use "derf" -- which is "fred" spelled backwards -- as my username on things. i'm actually not sure how i originally came up with that, but it seemed like a good idea at the time.
then at some point i bought derf.net -- derf.com was taken by a company called Derf Electronics, but both .net and .org were available, so i got.net because i figured "derfnet" sounds cool. and i decided that "fred at derf dot net" sounded cooler than "derf at derf dot net" (though of course the latter does reach me). this was around the same time i was setting up my first linux box, and so i made my account on that machine be "fred" rather than "derf". incidentally, i keep a page of links to other derfs at http://www.derf.net/otherderfs/ ...
meanwhile, on various websites where you can set up an account, i was often finding "derf" to be already taken. i think for a while, the second thing i would try was "nfp", but of course that was also often gone.
i think probably "neilfred" was the next thing i would try. i wound up with "neilfred" on My Yahoo! and AOL IM, which are easily two of the top five fullest namespaces (maybe #3 and #1, though i don't actually know that for sure; i'm pretty sure they're both fuller than the .com namespace).
at some later point, i realized that "neilfred" is pretty much unique to me on the entire internet, which is actually pretty amazing.
i signed up for "neilfred" on hotmail (which i imagine is the #2 fullest namespace), just to see if it was still available, and it was. web searches for "neilfred" (as one word) seem to turn up pages related to me, and pages where "neilfred" appears as one word because it's part of a filename, in which case it's usually either something to do with the folk singer Fred Neil, or else referring to two different people, one named "neil" and one named "fred" (for example, i remember finding a photo of two such people, where the filename was "neilfred.jpg").
at some point i bought neilfred.com, just because i'd be bummed if someone else had it. and i currently use "neilfred" as my username basically everywhere but my own box, where my account is still "fred"... for now, anyway. also i recently started using NeilFred as one word in my (offline) name.