Finally some Haskellish content!
Anyway, it's taken me a few times of tilting at the Category Theory windmill to finally start to grasp it. One of my friends requested that I let him in on what finally worked for me, so this is for him.
These videos by Steve Awodey were what really broke the logjam for me. Steve is good lecturer, and his presentation of the material works from the ground up. The best thing about those videos is that he gives examples of all of the concepts and explains what they are good for. I wish there were more of them; they don't cover a lot of ground.