Volumes 1-7 of the original series, the first three of the Duelist series and the Movie manga. A few action figures such as Exodia, Blue-Eyes Shining, Rocket Warrior and a buttload of mini-figures (the 2" ones). I also have the Dungeon Dice Monsters board game, some books on the game (i.e. Pojo's 2005 annual) and some card catalogues, puzzle books and a calendar from 2004. And of course, hundreds of thousands of cards.. the first Master Collection, about 15 tins, zillions of booster packs and a binder filled with 200+ foils.

Also two Duel Disks (one of them got broken) and a Chaos Duel Disk. And a bed sheet... =/
I retired from the game a few months ago.. it was conflicting with my social life and it was getting too expensive. Plus I didn't like the direction the game was going in, and how they made too much stuff based off the GX anime which I hated to death. And of course, it was time to grow up a little.

I'm gonna sell some of it.. but I get too attached to ones that are valuable to me (i.e. my first ever card, my first BEWD, a Time Wizard my friend gave me for my birthday, etc.)