Recommendable RPG's and supplements.

[Superfluous Crow]

The RPG market is crowded with a lot of different games, and it can be hard to tell what is worth having and what isn't, and that is the reason i've started up this thread. Especially when you live outside the US, the shops often don't stock all the types of games available and we might easily miss out on something if we don't seek it out ourselves. That being said, this thread is mainly just for sharing different alternative systems you've encountered and liked.
I'd like to start out by recommending Unhallowed Metropolis, a game i've mentioned before, which i like quite a lot even though i must admit i haven't found the time to properly try it out. It's technically setting-specific, but that shouldn't keep people from buying it as the setting is rich enough for it to serve as inspiration. The accompanying system is also interesting, and presents some new ideas. The game takes place in an alternative "future" where a zombie plague swept across the earth in 1805. England is one of the few nations that survived, and they are now holed up in smog-filled cities.  The gameplay consists of undeads, dark science, and the nature of evil. The technology is slightly steampunkish, and although it takes place in the future the civilization is sort of stuck in the Victorian age, and the technology has diverged more than it has progressed. An interesting game all in all, you should take a look at it.
And now i hope you can give some insight into some interesting games out on the market. (otherwise we'll just make them ourselves)  

[Matt Larkin (author)]

The Riddle of Steel for realistic combat, character driven gameplay (that is your character's motivations drive the game system), if not for its setting.

The Burning Wheel for semi-realism and neat innovations.

Shadowrun for diversity and crazy thrills.

Warhammer Fantasy Roleplay for an interesting setting and interesting character advancement mechanics.

I'm eager to try GURPS for customizability.

I want to try D&D 4th for ease of play. I've been impressed with the books but haven't gamed in the last few years.

Edit: Oh yeah, and Children of Fire for freaking coolness.

Also on the Campaign Resources wiki see the bottom for a list of game systems. And feel free to add Unhallowed to the list!

[Superfluous Crow]

oh yeah, i should have mentioned Riddle of Steel as well... I'm not really impressed by GURPS nor by DnD 4.0, even though i was optimistic about both to begin with. Warhammer looks really neat in many ways, and haven't read much about the rest.