The Orange Box is really the best value for your money if you like FPS games. Half-Life 2, HL2 Episode 1, HL2 Episode 2, Portal, and Team Fortress 2. 3 of those games aren't available in any other package, and if you like Half-Life, then the Orange Box is money in the bank as far as Value goes. Failing that, there's Bioshock, System Shock 2, and Condemned 1 and 2, all of which are great FPS games, and probably worth your money.
If you are interested in picking up a game like World of Warcraft, for the love of all that is good and holy, find a friend that already plays, and see if he'll recruit you. It'll give him a free month of play, an extra mount, and if you play together, you both get triple experience, making the trip to 60 a breeze.
Information about the Recruit a Friend program is on the WoW website
If you have a lot of time to kill, tactics games are good. Disgaea, Disgaea 2, and La Pucelle (and there's one more that I don't remember) as someone had said, but there's also FFT, Tactics Ogre, FFTA and FFTA2, all of which have their pros and cons, and will collectively eat a massive amount of time.
If you like Dungeons and Dragons, there are a slew of older games that used the Infinity Engine that are definately worth checking out, Baldur's Gate, Baldur's Gate II, Icewind Dale, Icewind Dale 2, Planescape Torment, Fallout and Fallout 2, the last 3 being in different setting then standard D&D. There's also Temple of Elemental Evil, which I'm fairly certain plays like the old Infinity Engine games, but isn't actually run using the engine, but it plays similarly.
If you like JRPGs, there's FFXII, Kingdom Hearts 1 and 2, Blue Dragon, Tales of Vesperia/Symphonia and Lost Odyssey. I also enjoyed FFIV on the DS, although I don't know if I'd suggest it for a buy.
I really have nothing else to say.