Browser Progress Bar is an Anti-pattern - The user initiates a navigation, and the browser gets busy: it'll likely have to resolve a dozen DNS names, establish an even larger number of connection...
#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.