M&M Supplements can be found right here. I can't say which are good, as I don't own any personally. But the core book is well worth the buy. I've GMed it once and it's already one of my favorite RPGs. Though I prefer creating my own NPCs,
Crooks is a great book full of supervillians, heroes, and mooks to throw at your PCs.
Here's the Modern
product list. Again, not too familiar with all of these books, but Modern is a good system as well. I really enjoy d20 Future, though I wish they'd paid more attention to some of the individual topics. It's an ambitious book to be sure, and overall I think Wizards did a good job with it.
Are you planning on using both of these books together? Though they use the d20 mechanics, the systems are a little different, and it would probably take some house rules and adjustments in order to fit one to the other. By and large, M&M is a much simpler system overall: classless, point-buy-based, and totally customizable. It's certainly doable if you wanted to import one into the other. Or maybe I'm just getting ahead of myself and you just happen to want both of them. Either way, hope this was helpful, and enjoy!