I've presented at TechCocktail before. It's a great experience. Here are a few tips:

1) It's in a bar environment, so you have to stand out. I had a big retractable banner (8 ft high) which stood out, so when you walked into the room people saw it 2) 20" monitor hooked up to a computer playing a slideshow is also great 3) They have to walk away with something. Stickers? Something fun? 4) Talk to anyone and everyone who walks up, regardless of their background + interest. It may not be for them, but they may know someone who is.