My favorite gadget at the moment is my Treo 600 PDA cell phone. It seems like my whole life is in there and at the convenience of being connected to my hip. It is a full PDA, and being able to hot sync it to my desktop is invaluable, especially if you have to trade phones out. No more having to reprogram all of my contacts. I have my full contact database and schedule with me, and it can also take pictures. There is also a memory card for backing up.
My favorite function is bei