I used to make fake report cards and sell them for $100 a pop. Make sure you overcharge, cuz if you don't, nobody will take you seriously and they'll rat you out. You can cash in on the losers that are going nowhere in life, make bad grades, and live off of daddy's endless bank account 😉
You can also fix computers. I don't recommend BUILDING computers, because then you have to support them. You're better off just fixing them. I made tons of money in high school (for being 17) doing this. With Windows 7 around the corner, I'm sure you can find plenty of people wanting to upgrade that don't know how, or are too scared to do it themselves because they think they're lose all their info.
The most immediate way to sell money is to SELL STUFF! Dig out your old crap that you don't want anymore and get rid of it for money. That simple.
Play any instruments? Perform (get gigs) or teach lessons. Performing is MUCH better, but do what you can.
Some people pay for taking care of their dog during the day while they're at work... I don't understand those people, but they're out there. Go find them!
^^ See? You've already made $.02