There's always my favorite supplement for Big Eyes, Small Mouth 1st Edition (the superior edition), Cute and Fuzzy Cockfighting Seizure Monsters.
No, I'm not kidding. It's a really solid piece of work.
Maybe not quite as good as Big Robots, Cool Starships, but up there.
I've seen the BESM book but haven't delved into it.
The supplements look very interesting, though.
In the spirit of complete revelation, I must admit that I actually have a co-author's credit on one of the 2nd edition books. (Hearts Swords Flowers. It's good; you should pick it up. One day I might even get paid by the publisher for my work. [I'm not holding my breath.])
The reason that I suggest that you should pay more attention to first edition than second is that the latter really took the "generic RPG core mechanics book" a little too traditionally, so instead of being just a slim pamphlet of core mechanics and very focused ideas, it wanted to turn into Hero or GURPS – along with being a several hundred page nightmare which tried to provide individual mechanics for everything under the sun. That didn't turn out to be a really competitive product, in the end.
Which was sort of a shame. I was looking forward to writing more stuff for them.