Okay, here's a few things. Keep in mind I haven't lived there in 10 years, so I'm bound to missing some cool places, but here are some of my favorites in addition to the aforementioned Highwire Lounge.
1. 40 Watt--Epicenter of the Athens music scene. A must.
http://40watt.com/
2. Trappeze--Great beer restaurant. Do not confuse with this Trapeze, a club in Atlanta where strangers have sex with each other.
http://trappezepub.com/
3. The Grit--Fantastic vegetarian restaurant.
http://www.thegrit.com/
4. Graze--One of my good friends just opened this gourmet slider restaurant. The food is really good and there's a great beer selection.
http://www.yelp.com/biz/graze-athens
5. Georgia Bar--No frills place, my kind of bar. It was a littler frattier than I remembered last time I went, but maybe it was an off day. Or maybe I'm 33 years old.
http://www.yelp.com/biz/georgia-bar-athens
6. Wuxtry Records--If you're a music nerd at all, it's a must.
http://www.yelp.com/biz/wuxtry-recor...xchange-athens
That's just a few places. You might look into restaurants like Clocked and The Last Resort, too. Oh, Weaver D's, too, for good soul food and the R.E.M. connection. Downtown is just across from UGA's north campus, too, which is really nice to walk through.