haskellonline.org, my recent experiment to make learning Haskell easier, has been doing quite well. More than a thousand people have checked the site out since my last blog post. Yay!
I have since prettied up the interface a little bit. The editor now highlights not just the line, but also the error token itself. Simple code folding is now available too: try clicking in the gutter (near the line numbers) on the first line of a multiline definition.