The Art of the Business Model - A good business model forces you to answer two simple questions: “Who has your money in their pockets?” And “How are you going to get it into your pocket...
#1 MerbCamp - Yes, all merbists have seen it.
#2 Merbunity - It's maintained by hassox!
#3 Atlanta ruby user - I found this site recently. I think it's worth to see.
#4 Merb Dependencies and Bundler - by
#5 peepcode (well, not free. but it's 9$) - The screencast was recorded on merb 0.9 but it still is a good one.
And there are good tutorials.