I have been waiting for a good online HTML/CSS editor for way too long and it turns out I've been missing out because ShifeEdit is ready for our Dreamweaver-ish tasks. I've tried it out a tiny little bit and it hasn't disappointed me in any of the ways that other editors have. It's disappointed me in new and difficult-to-explain ways. But they're not bad.
Overall a great start and I'd certainly use it on a commercial product.
Check out ShiftEdit, the great new browser-based IDE