I was stumbling through YouTube and wandered into Tampatec's channel. What drew me in was that he was/is on the hunt for Super Hero Squad Online codes. That sounds like a great place for code sharing and he's even doing things like giving away gift cards for when people give him new codes that work.
I watched all his videos concerning SHSO codes, and it appears most promotional codes are time limited as the following codes DID NOT WORK for me:
However, it was pretty cool to find a code that did work:
redeem it while you can! Tampatec's channel seems like it is definitely one to tune in to if you're on the hunt for the latest SHSO codes.