Okay, so one of the geekiest of my interests is something I guess you'd call RPG Archaeology. I'm interested in RPG's not just for playing them, but also from a game design perspective, and one of the interesting things to look at is the manner in which game systems evolve.
I've made it clear in the past that I think very highly of the RuneQuest system, and I think its game system is strong even by today's standards. But I'd have to say (granted, not having seen the new edition yet) that the pinnacle was 1980's release of the second edition. My copy was even more well-worn than my AD&D Player's Handbook.
So it was with great pleasure I found the RPG Archaeology site that relates the entire history of the RuneQuest game. It's an interesting read if you geek out on stuff like this.
Of particular interest to a RuneQuest fan like myself was the discovery that there was - sort of - a fourth edition to RuneQuest which was never really published. It was to be called RuneQuest: Slayers, and apparently had nothing to do with the series (much in the way Halloween III: Season of the Witch had nothing to do with the Halloween movie series), so it's probably a good thing it didn't become an official member of the RuneQuest line.
But it is available as a free download under its modified name, RuneSlayers, if you're interested in scoring a free, fully-developed RPG.
But as I mentioned before, I'm still looking forward to the Mongoose edition of RuneQuest.