Three different artists, three different studios, three blogs worth noting:
Colin Giles, an animator with Carbunkle in Vancouver, has started posting his work from Ren & Stimpy, with drawings and photos.
Eric Wiese, a director at Laika Animation in Portland, doesn't update his blog very often, but his artwork is so delightful I couldn't resist mentioning it.
Jakob Jensen, an animator and character designer at Dreamworks, is showing off his amazing talent and blogging about his drawing techniques.