My pride and joy is a 1992 Giant Sedona that I call Sid. It is about the most natural nickname for my bikes yet, and it fits her personality. Competitive but no lightwieght, capable of anything and getting me home from it.
The road bike is a 1986 Trek 400 that I call Allison. Road bikes always have a feminine side in my view, so it had to be a more girly name
The X-mart Next mountain bike that I play with as a beater I call Wally. Origin as well as personality.
2001 Giant XTC is still nameless. It has such a neutral handling personality it seems masculine, but I am still stumped for a name.