I started playing rpg's back in 1983. The very first games I played were Marvel Superheroes, Star Frontiers, and Moldvay's Basic/Expert games. I mainly played D&D, but the other two games definitely saw time at the table. I kind of miss those days. I had lots of free time, and basically memorized the books, I read them so many times.
I remember using The Isle of Dread and the Known World a lot, based purely upon what was in that module. I look at the giant hardcovers for gaming worlds that I read now, and it's kind of funny how much I just made up based upon a map and a couple pages of descriptions.
I also did a lot of stuff with Star Frontiers, especially making up stuff like bug aliens and playing a military game fighting them. It was a heck of a lot of fun.
I kind of moved on from Marvel Superheroes pretty quickly, as I found that at the time, I didn't really like playing superheroes.
The next big game I got was Middle Earth Roleplaying, from ICE. Gods, I had a lot of fun with that game. I only had a few of the adventures (Tharbad sticks out in my mind), but I loved that game. My friends and I played several awesome campaigns using that book.
I guess it's part of getting older, but I don't get that thrill from modern games any more. Maybe I've just seen too many variants of rpg's, but while I find them interesting, I don't find new stuff exciting. More of a "That's kind of neat." reaction than a "Wow! This is so cool!" reaction.