If you're a druid and need to go afk, change into your water form, and dive underwater. This is a great place to go afk on PvP servers. If you are away for too long, when you finally logoff, you will still be in water form, and won't drown. When you log back in, you will still be in the same form, and still safe. Just remember to go as deep as you can, and away from mob spawn points.