If you're looking for 'little' games (short innings, cheap)...
[/url=http://www.shrapnelgames.com/digital_eel/Weird_worlds/1.htm]Wierd Worlds[/url] is galactic conquest in 20 minutes or less...with procedurally generated levels and gobs of stuff to discover (to say nothing of the sumptuous audiovisual feast attendant to said gameplay) makes it a good use of $24.95.
Uplink is a delightful little paranoiac romp into the world of Black Hat hacking. Absurdly low system requirements, impressive amounts of exploration to be had, and works both as a marathon game or in short bursts. Highly recommended.
On the Total War note...if youre looking for epic strategy, politicking, assassination, and general skullduggery,
Shogun is buckets of fun and can be had in jewel-only form for $10 or less. For a game released in 1998, the graphics are poetry, and both the strategic and tactical games are immensely rewarding.
Command and Conquer: The First Decade can be had for ~$40 and will probably keep you entertained until the apocalypse. Nothing like Tiberium, Attack Dolphins, and the odd Toxin Tractor to lay waste to one's opponents.
Grim Fandango mad seconded. Or whatever we're up to.