I’m a big fan of Grist. They do a great job of aggregating the most valuable enviro news of the day, plus they write good stuff of their own (Dave Roberts‘ reporting on cap and trade v carbon tax is some of the best out there – oh btw Mother Jones has pub’d him too; ditto on Tom Philpott’s coverage of the swine flu epidemic ). They’ve also done a terrific job figuring out who they are, what kind of voice they want to have, and how they want to be connected to their community – and they’ve delivered on it consistently, year after year.
Offhand, I can’t think of a website with a more coherent identity than these guys: they’re smart without being in the slightest bit pedantic, funny without being nasty about it (must be something about being based out of Seattle), and they cleverly walk the line between a journalism organization and a community site. I was personally really pleased when Grist joined The Media Consortium, a network of about 50 indy media groups I was helping to pull together a few years ago.