Motorola (dunno which exactly) around '95, didn't use it much though.
Sagem (again, no idea which) around '98, stopped working after a few months
Nokia 5110
Nokia 6310i in early '03 (first phone i actually liked, before i didn't even have 'em with me most of the time)
Nokia 6680 around '06
Nokia E51 right when it came out, end of '07 (best phone-phone ever IMO)
Nokia 5800 end of '08 (with the new firmware release recently it's actually becoming a decent phone)
Nokia N900 dec. '09

hopefully i can keep this one for 2 years, but i'm afraid that Maemo 6 is gonna thwart that plan *g*