Have you ever tried Geocaching? There are so many fun geocaching sites around Dripping and the Austin area. Explore the Hill Country and find treasures galore - just remember not to take anything away from the Geocach unless you leave something behind to replace it.
Blues on the Green happens every other Wednesday at Zilker Park and is free! Great music.
June 12 is the Wheeler Brothers, June 26 is Black Joe Lewis and the Honeybees. July 10 hear Bob Schneider, and July 24 The Gourds will be playing. The final act is August 7 with White Denim.
Austin has several available segway tours - some include food truck stops and bat watching. You can frequently find a Groupon deal for these tours, and sometimes even without the groupon, they will give you the groupon price. Just call. This is good for anyone over 90 pounds - under 90 pounds and the segways may not work right. I was amazed at how east these things are to drive and how much fun!!
Any other ideas? Let me know and I can spread the word.
Interested in getting a group together? Again, let me know.