Ad:tech has a venerable heritage in the digital industry. It’s been going on forever — well, since 1997 — and it’s huge. It’s also very, well, direct response. That means lots of lead-gen networks, tool providers and sundry other characters. It is also, alas, perhaps the last bastion of “booth babe” in digital media events. Here are 10 telling pics from ad:tech San Francisco, which just took place earlier this week. A special thanks to Steve Hall, whose Flickr photosream was the source for most of these pictures, and Matt Barash who also snapped a few for us.