I was going to say Aloe Vera also. I just started selling a line of beauty/spa products that has a lotion thats suppose to be really good for sunburns also. Not sure this is good or bad, but I haven't had a chance to be in the sun much lately so I haven't had a chance to give it a first hand experience! If you're interested though pm me & I'll look up the info on it when I get home tonight.
I normally practically bathe in the aloe vera when I get burned!
It always seems like you get burned just before some kind of special event though, doesn't it?!