Transatlantic , a "super" group with arguably the greatest drummer around, the best guitarist, and on of the best epic song writers/keyboard players. What do you mean you never heard of them?
Another "Supergroup" that hasn't been mentioned so far is "Asia!" I caught them on tour two years ago as the opening act for Yes. Steve Howe played both sets! I don't think I've ever seen a concert where although the headline act was anticipated with great excitement, there was a huge disappointment when Asia left the stage. They played a terrific set of Asia's songs, but the roof of the Uptown Theater was nearly blown off when the "solo songs" were played: Geoff Downs had "Video Killed the Radio Star" which was a lot more fun than I thought it would be; Since Steve was going to play with Yes, he did an acoustic solo. For Carl Palmer we were treated to "Fanfare to the Common Man;" But I thought the place had exploded when we heard the opening for "Court of the Crimson King" for John Wetton.
I'm also rather shocked that Todd Rundgren, and specifically Utopia (certainly V1 with M. Frog Labatt, if not V2) haven't been mentioned!
Mark