Heroku: Rails development in a web browser, with hosting.

Heroku is too cool for school. I just got my beta invite this morning and I'm having a blast playing with it. It's a Rails development interface (basically a webified text editor with some shell wrappers) that runs inside your browser with AJAXy goodness, letting you create and edit Rails applications in real time. It's rather impractical from a real-world point of view, lacking features like version control, and IDE niceties like code completion, and I haven't figured out how to use gems without "vendoring" them, but it's still insanely fun to dabble with and show off to your colleagues. The migration management is rather clever, and the drill-down logging is nice. They are still in beta, but perhaps by the time they go public it might be a decent little platform for very simple deployments like Grandma's Flickr and Twitter mash-up. But putting all practicality and business potential aside, it's an impressive feat of programming. Kudos to them.