This has been kicked around a bit, but I couldn't find a thread for it, so I thought I'd give it a proper go. I know a lot of folks have said they'd love a Jack White-led Superjam, and another I heard that I liked was a Dave Grohl superjam. I was hoping for a Woodie Guthrie themed deal last year. But now I think that the best one for my tastes and the possibilities of what could be would be the Superjam curated by Jools Holland. He has a date as "Jools Holland & His Rhythm and Blues Orchestra" in the near future and tickets cost around 50 US dollars. Not sure if he travels to the US to play often though.
"When music affects us to tears, seemingly causeless, we weep not... from excess of pleasure; but through excess of an impatient, petulant sorrow that, as mere mortals, we are as yet in no condition to banquet upon those supernal ecstasies of which the music affords us merely a suggestive and indefinite glimpse."