Mage Macro or add on helpFollow

I rolled a mage yesterday, and I've been having a lot of fun with it. I was wondering if there are any good macro's that people use. For example it would be good to be able to set a target at the start of combat (for sheep), and then have a second macro which would change your target to your sheep target, cast sheep and then set the target back. Is that even possible with the current macro system (there may be trouble automatically switching back to the other target).

Also what add-ons have you tried and what works well?

I use metamap as a mean of easing off the search time of some locations in-game
I also have the total auctioneer bundle helps a lot to make profits at the AH