I saw some Oktoberfest kegs a few weeks back, and Bell's typically has them with Oberon in the summer and brown ale in the fall. Those are more expensive but the beer is better.
Now and then I'll see other craft brews in them. I can't recall whose, but it might have been Rogue Yellow Snow IPA... But I think that was like $40 for the mini-keg which is just too much IMO.
I buy one or two every so often, but I usually get the cheapest ones I can find and tap them for party/football game.
With the price of cornies going up, I'm getting back to using mini-kegs more often.