Party on 6th Street in Down Town Austin.. Lots and lots of people, lots of fun.. lots of live music... watch the largest bat colony in N. America poor out of congress bridge over the river downtown each night as the sun is gong down. Skydive at Skydive San Marcos.
Swim in Barton Springs, touristy, but visit Lance Armstrong's Bike Shop "Mellow Johnny's"... Visit the Downtown WholeFoods
If you like Music.. Come in August and go to SXSW music festival
Eat= Oasis Restaurant overlooking Lake Travis, Chuy's Mexican food, Salt Lick BBQ.. or Cooper's BBQ in New Braunfels, Amy's ice cream shop