GhostRecon.Net... you'll never guess which game I'm currently addicted to. While poking around for strategy guides, I turned up ghostrecon.net ... a very nice site, I must say. Good primary information, interesting background information (which is rare); professional templating and simple navigation. I'm impressed!
While I'm on the topic (games, that is) I'll also mention the Rogue Spear walkthroughs on Pie's Tactics, pretty helpful if you're stuck (hey give me a break, I only just got a machine capable of handling these games ;)).