I'm fairly certain Diaglo is an AI program which hasn't been updated since 1975.
That said, I've toyed with the idea of revamping the entire thing.
I'm coming from the position that the way skills work suck.
The way magic works is too generic. The overal power level is too high, and the DMG magic items are all too cliche.
Given that, my next campaign may be built from the following:
"Buy The Numbers" - to allow for a more detailed, less stifling approach to character creation.
"Elements of Magic (revised)" - I may apply this as mandatory for charisma-based casting, and keep the "fire and forget" system for int-based casting, since that seems to make sense in my mind.
"Artificer's Handbook" - for magic item creation rules, and new magic items. No more +1 rings of protection. AH will allow me to create unique items, each with personality and a back history. Plus, it has rules for low magic built right into the system.
"Magical Medieval Society: Western Europe" - to help facilitate world creation, and it will allow me to create a more believable landscape within which to play.
Now, having said that, I would like to also remove the d20 from the game, and replace it with a d%, since that would allow for so much more flexability. In the current system, masterwork studded leather is as good as chain shirt, which makes no sense. Having an AC that could go to 100 allows for much more subtle variation in ACs. Leather armor could come in "poor, tattered, average, high quality, and masterwork" variations, for example.
Obviously, replacing the d20 with a d100 will take me a lot of time, but I think if I implement all the above, I'll end up with the perfect system that *I* want to see.