I know I did this many times with my twin to make a quick buck. I remember that people would always stop by in their cars and give us like $5 bucks for a cup of lemonade just to be nice. I was pretty tech savvy as a kid too, we one time made a big banner on the computer and printed it out on a numerous sheets of paper to make our coffee table look more snazzy.
Did you ever do a Lemonade Stand or something similar when you were a kid?