Iphone 2g
I still have mine, and I still use it as my main phone, jailbroken of course!
I bought it off Ebay after the 3G came out, and I figured that it would be a bit cheaper just before Christmas, as people madly tried to get rid of them to get a 3G for Christmas.
I started out without a contract, using my old sim, so had to jailbreak and unlock as soon as I received it. I have never had data, which sounds a bit odd, considering it's almost crippled without data, but I didn't see the point as I have wifi at home and at work. The only time I miss it is on holiday.
Since then, I got a company Blackberry, but found it a pain to use, so move the sim over to my iPhone (without data still).
I have also bought an iPad which has taken over most of the internet stuff I used to do on the iPhone. I think at some point I will need to get a new phone, but when? And would it be worth thinking about an Android? Heaven forbid....