Just a note before I leave for teh south "shudder". Spiderweb software is running it's annual sadness sale. When the fall comes it's not a pretty sight in Washington so they run a sale to cheer themselves up. 10% off everything in the Spiderweb store, that includes, discounted bundles, CD's, and hint books. If you've been on the fence about some of the RPG's Jeff Vogel makes, now is your chance to nab a few up at a nifty discount. These games are hella lightweight too, If your computer has been made in the past 10 years you can play these gems. Hell most of them you can probably play on machines made in the past 15 years.
Personally I'm a huge fan of Nethergate, it's got some of the best story around RPG wise. Play as the Romans or the Celts, and get a unique view of the story from each side. Runs on a modified BoA engine which I am a fan of, it's easy to navigate and control via keyboard commands.
Other than that I really dig all the Avernum games, though for whatever reason I tend to like 1-3 a little more. 4 used a new, slightly less retro engine and I tended to like the old Avernum engine. I found it quick for me to navigate with the keyboard commands. Don't get me wrong 4 is still fantastic, but 1-3 for sheer retro content goodness.