If you are doing trade shows - and I don't think they're completely out of fashion just yet - one thing I've found that works well (especially if it's a smaller show) is a raffle. The goal: get some qualified prospects and make a friend.
I usually have a very brief form for people to fill out if they're interested in entering - keep the questions straightforward and simple. Don't ask for all the name-rank-serial number questions you can think of. Stick with name, e-mail address, and (maybe) phone number. Ask a couple of important qualifying questions that determine whether this person will ever be a prospect (or just wants a chance to win something).
The prize doesn't have to be huge, but should be something that makes it worth a partipant's while. Gift certificates (LL Bean, Amazon, etc.) are always welcome - plus they're small and portable. (One reason why your raffle might not work as well at a big show is that your shoestring prize may pale in comparison to the Mini-Cooper or trip to Bermuda that someone with a 40x40 booth (with a 40x40 budget) is raffling off.
I will confess: I always go through the "fishbowl" (or wherever the raffle tickets are tossed) to weed out the completely unqualified leads. No prize ever goes to someone who's not a potential buyer. (One time I won a trivia contest that I took part in in a competitor's booth. It was pretty clear I was with "the enemy", having made no attempt to cover my badge. Winning the initial contest meant my name went into a drawing for a video camera. I won!
Nice to know that the raffle wasn't rigged. Embarassing to think they didn't know that we were a competitor. And surprising to see that they'd let me win. Still have that camera! Thanks, Global Crossing - and what can I say? They're still in business, while Genuity, which is where I was working in the day , is no longer among the living.