I've got a couple:
Freelancer [http://en.wikipedia.org/wiki/Freelancer_(video_game)], it was an awesome space simulator that was a spiritual sequel to the Starlancer series. Sadly some features such as a dynamic economy and more open world elements were cut because Microsoft wanted to meet a release date. Regardless it is a fun combat sim with great exploration elements, plus the graphics for the backgrounds still look beautiful eight years later.
Gladius [http://en.wikipedia.org/wiki/Gladius_(video_game)], You lead your own gladiator school in competitions across the globe and recruit various people to your school. While the plot doesn't really kick in until half way through, the game in my mind is one of the best tun based tactics games around.