Whenever I needed quick cash, I'd clean my sister's house (she's pretty messy, and likes to have me do it because I'm a neat freak). She'd give me between $20 and $40 depending on how much I did, and how much she could afford. I'd also babysit.
I also tend to put things up on eBay that I'm no longer interested in. Sometimes it works, sometimes it doesn't. Eh.
Whatever you decide to do, good luck!