Multi-mob tanking is an essential skill for effective tanking, acting as crowd control for 2 or 3 mobs and stopping them from squishing the clothies! It also seems to be topical, as there are a couple of recent excellent blog posts on the subject.

Karthis at Teeth and Claws (who I’ve linked twice now and I really need to add them to the blog-roll) has a post about multi-tanking macros for feral druids.

Meanwhile, Tank Hard has tips for warriors tanking 2 or 3 mobs in his primer for multi-tanking for Warriors