Couple of possibilities here that I think would work very well.
If you want to stick w/ d20, I'd recommend Spycraft 1.0 (and for pulpy goodness, get the Shadowforce Archer campaign supplements - chemical monsters, mystics, mysterious cults, and psionics that don't suck like standard d20 psionics.) Spycraft 1.0 is based upon 3.0 rules, so if you are a 3.5 purist, this may not sit well. It is out of print, but available on DTRPG/RPGNOW.
As was previously mentioned, TORG. Yes it is out of print (but you can get on DTRPG/RPGNOW). It pretty much has one set of supplements specifically for pulp stuff (we're talking power-mad criminals with large organizations of henchmen, weird science gadgets, and super heroes.) The system is easy to learn and easily scalable.
Another option if you are focusing on simulationist/gritty WWII moreso than pulp is the Twilight:2013 rules. I highly recommend them, especially the Life Path system for character generation and the team rules which pretty well simulate military small unit command and control. It is kinda like a combination of the d20 "teamwork" rules and the "in this situation, we do this" immediate action/reaction drills that parties always come up with (e.g. "When opening a door, the rogue listens. If there is noise and it sounds like hostiles, the plan is that the cleric and fighter will kick in the door, followed by the wizard casting a fireball and the rogue firing his crossbow at the closest target.")
Another option (which I find a bit too generic) is d20 Modern with the d20 Past supplement.