Mighty Empires, by Games Workshop
Modular, plastic 3-D terrain hexes that let you create your own world. Arrange them how you like, paint them, and make that 3D map of your home brew world, regardless of what game system you play. Yes, there are rules, which I'm told blow, but rules aren't necessary for something this cool. I've got this campaign world I've been thinking about for months now based on ancient Lebanon. I may never get to run it, but man would it be cool to map out with these!
Critical Hit Deck, by Paizo Publishing
You've got a deck of 52 cards. When a critical in D&D is scored, you pick a random card. Each card has various weapon damage types, including magical effects for spells. You use the card description instead of the typical damage amounts. For example, I just pulled a card and for a bludgeoning weapon I got:
Crushed Intestines: Normal damage and 1d4 Con bleed (DC15 Fort negates, save each round).I use the deck in my D&D game and the player's have insisted that I use it against them as well as for them.
Late War US Decals, from Battlefront
They have them for the Brits and Germans too. These add some character to my armor that I've tried to fix by buying other company's decals. The names will mix well with my other decal's names.