This phenomenon seems to be more prevelent with guitarists than bass players, but I was curious what you think. Guitarists can't ever seem to have enough guitars. I know this from personal research.:-)

Are bass players the same way? Do you have/use more than one bass? If so, why?

I'll start - I have a few:
Red Bass Collection with EMG and Active EQ (a broad range of tonal possibilities)
Rogue - Hofner bass copy (when I'm in a Beatle mood) - the only bass I would use when playing with TLT :-)
8-string silver sparkle (like the Cheap Trick one - neck heavy and unbalanced, but a nice complement for folksy and pop arrangements
Fretless - one I made with flame maple and koa - this thing growls!

Each has a unique tone and depending on the song and arrangement, I'd choose the appropriate bass.

Your turn.