My observations on this very important topic:
Salt Lick - Driftwood, TX
I think I've been half a dozen times, and am always incredibly satisfied. I'm not sure if I'd classify their actual BBQ as the best, but the overall experience (including the atmosphere) has to be my favorite of all. Usually, by the time I get back to Austin, I'm already feeling the effects of a BBQ hangover and need to hoist myself into bed.
Kreuz Market - Lockhart, TX
I've only been once, but I thought the meat was incredible.
Rudy's - Various Locations, TX
I've been to two Rudy's -- the original (I believe?) out on Boerne Stage Rd (I think ) NW of San Antonio, and the one in New Braunfels (which is our traditional post-Schlitterbahn dining experience). For a chain operation, I think Rudy's delivers prettty darn tasty BBQ. The cream corn is good too.
County Line -- Various Locations, TX
With apologies to William and others, I haven't been impressed with County Line the two or three times that I've been. The meat was dry and the prices seemed a little out of whack for what they had to offer. Maybe it's just that BBQ in a dining room isn't my thang.
Cooper's Old Time Pit BBQ -- Llano, TX
I liked the choose your meat component of Cooper's, but had less fondness for the bill. I can tell you that I was a little too ambitious with what I picked out, but I still feel like I paid more than other places. By and large, I thought the BBQ was good though, and I'd certainly go again if I found myself in Llano.
Angelos BBQ -- Fort Worth TX
I've eaten here twice. It provides an interesting juxtaposition if you've just been to the nearby Modern Art Museum.

Anyway...I have not been particuarly impressed either time that I've been. And, I don't feel that it's a very inviting place.
Sweatman's BBQ -- Holly Hill, SC
I'm amazed that this hasn't been mentioned yet -- this SC mustard based barbecue has to be one of my favorites of all time, and I always thought it was considered one of the tops in the state as well.
Woodrow's -- outside Tuscaloosa, AL
Previously mentioned -- this hole has incredibly good BBQ. My father and I were in the middle of a BBQ roadtrip (and coma) when we stopped by, so we weren't able to appreciate it in its full glory -- but I still remember it as being very good.
Curtis' All American 9th Wonder of the World BBQ -- Putney, VT
An odd location, but truly phenomonal BBQ served out of a school bus just off of I-91. It's not in the South, but I thought I'd mention it here anyway.
[This message has been edited by snorkmaster (edited Jan 30, 2004).]