Before you sell it, can I put my 2 cents worth in (Sorry - I'm in the UK, so that should read tuppence!) - Little bit long this!
I got the GP32, and I can agree that it doesn't get used very much.. Not to brag (And please - It isn't... I'm making a point here!)
I have:
PC (Anyone else think that Unreal 2 was naff? Excellent GFX, good speed - Rubbish game!)
XBox
PS2
Gamecube :angry: I sense another N64 coming on here!
Dreamcast (Remember those - You know, the one with MSR on it - Way better than the XFlop sequel PGR!)
Gameboy Advance (SP and Original)
Sony Clie PDA (Which I use a lot for books!)
And yes - The GP32... Which, in all fairness, gets used the less out of all of these...
BUT (And like myself recently, it's a big BUTt

) - It's damn handy for what it does. (And come off it - It's not even like it's mainstream - It isn't available over here in the UK nor in the States, so it isn't being supported like the other players!)
When... (Not IF) when the Genesis (Megadrive over here) and SNES emulators get to maturity, it'll be an excellent little device - Heck, it'd play DKC (Donkey Kong Country) better than the recent GBA port-over, due to the better screen! And the PC Engine emulator is great... Not too sure what I think about the ST /|\ emu just yet.
It plays movies - Let's see my little GBA buddy do that... Okay, so it can in a way, but not the whole of the Matrix
Scumm (No - Not you!) - DOTT... I finally managed to get around to playing this game - Never did when it came out, but I have now!

And yes, I have it for my PC too, but it was good playing on this little device. Sam n Max comes next!

It's soooooo handy not having to wait for the PC to boot-up. Switch, on, click, play!
While all the above can easily be done with the PC, you can't carry the Matrix around in your pocket - Even with a Laptop - nor have the ease of turning on and playing a good emulator game!
You might not be using it much now - I know I'm not - But you'll find you might just wish you had hung on to it later on down the road! (Believe me - I know the feeling... Do I wish I could play Goldeneye again - Don't call me daft, but I loved that game... And I really can't find a good quality second-hand N64 anywhere for the money it SHOULD go for, not the rip-off prices they do go for now! - Enough about that though!)
Right - So you want to get rid of the GP32 for a camera phone... Got one... bored! 'Nuff said! <_<
Please think about what should be made available in the next year - And ask yourself if you'd want to play whatever may come out. If you still don't want to, then sure - Go ahead and get rid of it. But NOT for a stupid phone, for the love of god! For a GBA I might understand, but not something that will quickly become unused more than your GP32. (Almost sounds like a double-negative!)
I was umming and ahhing about getting one, as I thought I'd be useless next to the Nintendo unit, but the GP32 has it's moments. (Movies and Funny adventure games aside!) - And it'll be used a lot more when I can put some Nintendo or Sega games on it!

Oh - And whatever film I so desire next. B)
Please think long and hard (You there, at the back - Stop sniggering!) before you get rid of it! Give it time!