Book of Nine Swords. It was the first attempt to get "martial powers" into the game and bring some interesting variety. Consider picking up that, and you're set for 3E. It was, of course, inspired by the 4E mechanics that were in the process of being created, and was a first test-bed for them.
Well, actually...
First, apologies for not reading every post in this thread.
So I have my name on the cover of Bo9S. Is it like the book that I wrote? Yes and no. The truth is that WOTC feels free (as they should, since they own the property) to "rip the arms off your baby, but it's ok, we'll give it new robotic arms that are much better" when you turn in your work as a freelancer. The quote is from Mearls, I believe, at a Gen Con 2006 or 2007 WOTC freelancers-only seminar.
The truth is that, speaking only for myself and not Rich Baker (who is great) or anyone else, I was trying to do with Bo9S exactly what the OP is talking about. Namely, work on a new melee power system that would function with the existing 3.5 spell system. The new power system would, I hoped, make melee characters more interesting and less overshadowed by casters, especially at high levels. It's neat that that system wound up being seen by most as very similar to and having influence on the 4e power system. But I didn't know anything about 4th-edition at the time.
So, Mustrum, when you say Bo9S was inspired by 4E mechanics, all I can say is that for me, it was not. On the other hand, at the time I started working on Bo9S, Rich already had a basic power system in place. Maybe he took that from internal 4e testing. I don't know. Also, maybe after my final turnover, the devs took it and decided, "Hey, let's run this through the 4e-ifier!" After all, as I said above, the final book is different in significant ways from the book I helped to write. All I can say is that from my point of view, the work I did on Bo9S was not inspired by 4e at all.
It was, however, inspired by exactly the sort of idea that the OP is talking about.
Edit: I'll also add that I think the 3.x combat/magic system was ok without Bo9S. That is, it was possible to balance fighters and wizards, for example, in the same party and in the same adventures. We certainly did in all my games, and it sounds like Psion did too. But my hope was that Bo9S would make it easier and more interesting to do so.