Seriously-wash cars. A friend and I did this one summer in high school when our parents threw down the 'you need to get a job' gauntlet. We spent about $30 on washing supplies and used a vacuum we already owned. We made cheap flyers and stuck them all around town and would wash cars at people's houses. Basic wash was something like $30, then we did something extra for $50 or so. We did very well...recouped our initial investment in two washes and then made lots of beer money. We also satisfied our parent's demands. One could easily make $200 a month doing this, and if they really hustled could make three or four times that much. Just a thought.