I already have the Aviary Flash-based photo editor on The Best Sites For Online Photo-Editing & Photo Effects list.
Today, though, they unveiled an HTML 5 photo editor.
I don’t really understand the difference, but I’m adding their new one to the previously mentioned “The Best…” list, anyway.
The HTML5 version can be used on an iPad, the flash version can’t. I’d expect a lot of tools will be making the switch either with an html5 version or an app for the iPad in the next year.