Baldur's Gate: Dark Alliance - A hack and slash set in the Forgotten Realms. It is NOT an RPG, and it is NOT based on the D&D rule sets. Some hated it, I was one of the ones who loved it. And excellent hack and slash that lets you choose from either the Elven Sorceress, Dwarven Fighter or Human Arcane Archer (which is impossible in D&D, I know).
Champions of Norrath - Dark Alliance 2 sucked. CoN was the spiritual successor to Dark Alliance and it rocks. Set is Everquest's world. Very similar gameplay, larger range of character, great game. Also has a lacklustre sequel.
Drakan: The Ancient Gates - A great adventure game. You have two playable dragons, the human Ryn and the Dragon Arokh. You control Ryn directly but can call Arokh whenever you are not indoors and use him to fly around, destroy normal enemies or fight hostile dragons on even footing. It has a great exploratory nature, I think, and I really enjoyed it. One of my all time favourites.
Final Fantasy X - If you like JRPGs, I recommend FFX. I thought it was the best in the series, personally. I know there was a big rant about it here on the forums the other day. I disagree with that guy. This game is great.
Primal - Primal is a puzzle solving/adventure sort of game. Not a hundred percent sure how to describe it. You play as a girl, Jen, who is attacked by a demon with ehr boyfriend Louis as they leave a club one night. Jen slips into a coma and her spirit is taken from her body into the realms of demons by another demon, Scree, who you can also control. Jen can fight, navigate narrow ledges, and eventually transform into four different demon forms which let her do other stuff like jump really high, swim (like a dolphin) and control time. Scree can lift heavy objects, climb on some types of stone (it isn't a sandbox game, so all of them is out) and possess statues to manipulate then. You control the two of them though four different demon realms, using the other to get ahead and do shit at times the other can't progress. Seriously, this game is fucking great. I have never played anything else like it. If you get any game from my list, let it be this one.
Resident Evil 4 - The best game in the RE series. The protagonist is awesome, the game is actually difficult (Fucking RE5!), it has good atmosphere, it is nice and long, the upgrading system is fun (if frustrating sometimes) and this is all things told one of the best games of all time. Primal might be my favourite, but this is closer to technically perfect in all regards.
Soul Calibur 2 - I have both 2 and 3, and I consider SC2 to be vastly superior to SC3, even without the customisation system.