There's been a barbecue place on 620 near the intersection with N. Lake Creek Drive for years. It's been known as Round Rock BBQ, and various owners. The quality has generally varied from mediocre to awful over the years. Some time recently, it changed hands and is now known as Johnny T's. Having eaten there now about 5 times, I think it's a really good place; a definite improvement.
I like the pulled pork and usually always go for that. The brisket is also very good, as is the chicken. The sausage is nothing special--although I usually get it because it makes a good "side" with the pulled pork. They have the usual sides: the fried okra is pretty good, and something we usually always get; the potato salad is good but nothing extraordinary. What really surprised me is how much I liked their cole slaw; usually I don't like cole slaw and don't order it, but had some that my wife ordered, and liked it a lot. The cole slaw and okra are likely to become my standard sides.
The place is small. We usually do takeout, but it's comfortable enough for a quick, informal lunch. The access is easy to miss, but they've improved it recently with more signs advertising themselves.
Incidentally, my very first post on chowhound. I've posted occasionally on the austin.food usenet group.