I might get stoned for saying this, but...
My group is currently playing a World War II Supers campaign using the net PDF Deeds Not Words for the d20 system. We are playing the gritty campaign mode with mulitple GMs. Each GM runs a one-shot adventure with his own PC doing some support role away from the main group. We started in late 1936 and are currently in spring of 1938.
I just ran an adventure where the group entered Austria via Switzerland about a week after it was annexed by Germany to rescue a Polish-Jew scientist who specialized in genetics and mutants and get him across the Danube River into Czechoslovakia.
Thus far we have had a really mix of fights and PC's. Some of the PCs are bruisers (Experiment and Supernatural Origins) and some are regular people (Baseline Origin).
We originally started a normal supers campaign with the d20 net PDF Powers Overwhelming, but quickly called it Powers Overbroken and abandoned those rules in favor of Deeds Not Words.
There are two supplements for Deeds Not Words: Laying the Smack Down and Bold Costumes, Black Hearts.
Supers is the least favorite genre for me (literary and RPG). However, I found that the combination of World War II, gritty campaign mode, and mulitple GMs have really sparked my interest in this type of Supers campaign.
Anyway, if you're looking for a decent supers rules set, and don't mind d20 system, then you should check out Deeds Not Words.