[coww-cho!!!!!]

Musical Instructer
If you know how play a musical instrument, post up ads on craigslist, at a music store, tell a friend, etc Charge $50/ hr and teach basics so they come back for more

T-Shirt Design
Buy a silk screen machine, learn to use photo shop (free trail for 30 days at adobe.com) make a few simple designs before the trial ends sell your shirt to friends for like $7 or better yet offer your services to bands and charge a $50 set up fee and then do your own package deals. obviously you have to buy blank shirts in bulk from a company. you can start out by going to a swap meet buying 4 shirts for $10
This is how my buddies got started with there brands (Nefarious Clothing and Fatal Clothing)

Photographer
Learn how to use a Camera something simple like a niikon d90. make a profile and offer your services to friends preferably a wedding because there are tons of people there to make profit from

Knitter
There are books you can get at fabric stores along with youtube vids that instruct how to use these things called "patterns" that can be downloaded or bought from users on forums or blogs. Theres a site called Etsy.com that allows users to sell items they make at home. you just need a paypal account for transactions.

It's super easy and ridiculous how my gf saw a simple wallet for $20 that she saw online. it was this see clear vinyl wallet that had a design inside it, but the design a piece of printed paper and the wallet was sewn together so its a very simple and cost effective design. you can also knit beanies' scarfs and what not and make profit from something that costs $1 to make

wood/metal artist
Basically make things out of wood and metal such as a simple birdhouse, work table, guitars (very simple i made one myself), fabricate things like roll cages for people here and other forums even though you don't own that type of vehicle.

Mechanic
do this only by word of mouth since to professionally do this i believe you need to be ASE certified or whatever. anyways you can make like $50 for something as simple as changing brakes or changing spark plugs. there are always people at work/ school who have problems with there own car.

graphic artist
There are small businesses that need to promote there own business and they need business cards. all you need is photoshop. ask what the customer wants for example for an autobody shop the owner would like a hotrod but would like you to put flames along its side and a dragon .......this would be super easy on photoshop and put flame like words of the autobody shops name with a black background and there is an oinstant card, find a independent printing press firm and get the cards made same can go for chinese shops that want you to design there menu and the ideas go for days

What if you don't know how to do any of these?
take a class at your community college about anything its cheap, fun, and you can hook-up with chicks! lol
Oh and you can always post your ad for free on craigslist