I've read through a few Haskell tutorials before but when I heard Brian Rosner was going to do the Introduction to Functional Programming MOOC on edX (which covers Haskell), I thought I'd join him—the first time I've had a study buddy for a MOOC.
The instructor is the legendary Erik Meijer who I've decided is the Yang to Guido's Yin amongst Dutch programming language designers :-)
I may be one of the few programmers who studied Category Theory long before Haskell :-) (not that we've gotten to any Category Theory in the MOOC yet).