Sure, youngin'!
The JSA, or Justice Society of America, are a super hero team in the DC Universe made up of Golden Age characters, and their legacy characters. Current members include: The original Flash, Wildcat, Hawkgirl, Power Girl, Sentinel (the original Green Lanter, Alan Scott) and more.
You can find more info here: http://www.dcuguide.com/Who/JSA2_Bio.php
Verily!
For Invaders, one of my favorite series at the moment--it has just started. Though many of the characters have histories that started 60 years ago, they are mostly just now getting reintroduced. They are in essence new characters, and you can jump aboard now and be with them at the start. The story arcs are short too, which is a plus, IMO. No waiting half a year to see fruition. As I see by your avatar and sig, you're a GI Joe fan. The Invaders run their operations aboard the Infiltrator, a state of the art battleship with sub-space capabilities, they can be anywhere in the world in seconds and do whatever they want, and with a coalition of 5-6 armies, massive shit will go down. The characters are fun, and the writer has a great grasp of them. The art is an acquired taste, but pick up the newest issue, #3 for an astounding fight and the conclusion to the first arc.
JSA is a coalition of superheroes much like JLA, but with a richer more in depth history. They've got their mansion and a family feel, with the old fogeys teaching the new heroes and some great stories. I believe a JSA/JLA crossover event is coming up next year, fun for all!
Forgot to mention this the first time around, Snakeeyes, and anyone else watching.
http://members5.boardhost.com/GAMS/
Message board based around the Golden Age Marvel characters. Allan Jacobsen, the writer of the new Invaders series stops by often. The boards are easy to use, no password or registration required, so come on by and see what's afoot.
They do have a WW2 history, as the original JSA was a team active at the time.
A couple of the members have been returned to their youth, Sentinel and Wild Cat. The original Flash is old and is mostly an advisor. A lot of the heroes now are legacy heroes, people who are the second or third to take up the mantle.
Some old foes reared their ugly heads at the original Sand Man's funeral, this brought the new team into action, and they decided to stay together, facing a myriad of difficulties.
The Mighty Destroyer, shows up this month in Invaders. A hero concieved of and active during the 40's, he was later utilized by Roy Thomas in the original Invaders series. Since then Fabian Nicieza had him become the head of the V-Battalion, a secret army formed to protect the world from hidden terrors. Roger Aubrey returns to help the Invaders face off with the legacy of one of their deadliest enemies...Baron Blood!
While the JSA help a weakened Spectre as Hal Jordan's new policies of redemption vs. vengeance let loose the hordes of souls previously damned by the judgement of the original Spectre, Jim Corrigan.
Surely.
http://www.geocities.com/newinvaders/
Some miscellaneous Marvel Golden Age sites, that include most of the Invaders members.
http://www.geocities.com/Athens/Olympus/7160/gaguide.html
http://www.geocities.com/brandechh/
If any of the characters you're interested in aren't detailed within those links, just ask and I'd be happy to help in any way possible.
Coming up in the next Invaders issue (#6) as an Enemy of the State tie-in, Wolverine tackles some New Invaders forces in Mazikhandar, a country the Invaders previously overthrew and took control of. I've heard there's supposed to be a sweet fight between Wolverine and Namor, with guest artist Jorge Lucas on helm. So everyone buy it and give it a shot, it's a stand alone issue (despite with solicit's may say, it is just part 1 of 1) and with a more mainstream artist. If Marvel sees a good bump in sales because of an artist geared towards regular sensibilities, maybe they'll get their act together on the title! Please, my compatriots!