Thought I'd share this product I use at most festival/farmers market gigs:
http://www.amazon.com/Coleman-2000003098-Pack-Away-4-In-1-Table/dp/B002YXR766/ref=sr_1_1?ie=UTF8&qid=1337269858&sr=8-1It's two small, oblong tables that can be used seperately, or combined to make a square table or a longer "banquet" table. They also have adjustable heights. I set them up in an L. One table at the highest setting on my side, which holds my rounds/hearts organizer, water, and card holder. The other table is set to the lowest (just over a foot) and goes in front of me to hold the tip bucket, but more importantly, to keep the kids at bay. I'm sure we've all had to constantly tell the kids to back up, which they do for a minute but crawl right back up. At the low setting, it doesn't break my connection with the kids at all. I can see them perfectly, measure their heads and fit wearables on them with no problem. They tend to sit on it but it supports plenty of weight. They pack together and can be carried like a suitcase.
I really do love these things and use them plenty for camping too. The only complaint I have is the adjustable height it done by unscrewing sections of the legs and not a slide lock system, but those I'm sure jam after a time.