People seem to be addicted to having the most fancy and modern gadgets they can get their hands on even if their old one still works fine. So, there are a lot of working cellphones out there and they have some quite cool parts in them. My brother (ALPHA G33K) and I discovered a very easy way to get them which I will share with you.
Step 1: Get the phones
Cellphone dealers (I get them from Rogers wireless) get old phones brought to them for recycling and they usually have a box of them stashed somewhere. I would recommend bringing them some sort of peace offering or baksheesh when you go. We just told them that we liked taking things apart and were wondering if they had any old cellphones we could have. They willingly showed us their box and said we were welcome to the contents and could come back whenever. BINGO!
Step 2: The parts
So far most of the ones we've gotten have actually worked which is kinda fun in and of itself but, my favorite part is the battery. They are small and powerful lithiums and if you have the right charger, you can charge them up in the phone and then they can be used for projects. Of course you are not likely to have the right charger on hand, but there are often chargers in with the old phones. If there are, you can get the matching phone. They also have a neat LCD, a speaker, a mini camera and a mic. I haven't actually got one of the LCDs to run off of an Arduino yet but I'm pretty sure it would be quite possible.
So there you go. Good luck!