quick! I'm going to western ireland tomorrow...

...galway the surrounding area specifically.

what are some must-sees?

I fly into shannon friday morn and have 4 full days...

Sorry I'm in a big rush myself but if you check these sites I've listed they might help:
www.citylink.ie/guidegalway.htm
www.tripbase.com/Things_To_Do_In-Galway_Ireland.html

Then again you could just go to quay street, drink a few 'easy' pints in neachtains and a bite to eat in McDonaghs. Or take the ferry to the Aran Islands (the weather is to be not so good this weekend though) so what!!!!
A day trip to the Cliffs of Moher in County Clare.
Don't worry you'll find lots to do.
Sorry I can't be more specific at the moment.

Killarney, Dingle, and the Dingle Peninsula are the best!!!! And of course the Cliffs of Moher