Most people think Rifts is the ultimate kitchen sink game and in many ways it is. However, the greatest gonzo game in terms of raw inspiration in a small package is Lords of Creation by none other than Tom Moldvay. The art at the link is from the game and if those pictures plus the rules light set of your choice can't spark adventure I probably wouldn't enjoy your table.
D6:Another great description of why D&D (and games like it work)
After playing some indy games Zak decides:
I think D&D works like this: the rules, setting, and DM are relatively serious (or at least intense) so you--the player--don't have to be. You can be drunk and play the goofiest half-troll half-gnome bard in the world and the game will keep chugging along and being a game full of twists and challenges and unexpected delights for all (including the drunk gnome) because it's pre-loaded with serious business.
I think that's a pretty serious insight both into why D&D is top of the heap (which Pathfinder outselling branded D&D doesn't change. I also think this explains why Palladium survives...it's this attitude turned up to 11.
D8:Forget the drip, she'll cost me XP
The Land of Nod presents a very interesting alignment system which provides XP bonuses or awards based on behavior. Better yet Matt walks us through it's logic so you could easily adapt it to your own worldview.
D10:D&D is Dead
Over at "I Waste the Buddha with my Crossbow" a declaration of the death of D&D. What's interesting is this is a pattern I've seen in the boffer LARP world twice with Amtgard (which survived it) and with Dagorhir (which split into two organizations, Belegarth being the other). When you create something that isn't a thing unto itself but a platform for others to build on with their own imagination you run this risk when you release it, that one day it will have a life of its own separate from you. You can either embrace that and be a light in this new world or try to take it back and make all the rules. I have yet to see the later succeed.