Trade shows are HUUUUUGE for a webased business. You have no store front to get your name out. Advertising and word of mouth are all you got. Trade shows are tremendous because you usually can only go to ones that will have your target audience. Not only can you attract new customers but you can build business relationships that will help you run your business better.
I have met so many people that I now do business with regularly at trade shows. That is just as important as attracting new customers.
To find trade shows in your area, check out a site like http://www.tsnn.com/
If you are seriously considering it, checkout http://www.atlanticexhibits.com/. They can build you a professional exhibit and give you invaluable advice that will prevent you from wasting time and money.