Have a yard sale
Sell just about eveything your willing to part with
Look for odd jobs or try baby/pet sitting, mowing lawns etc.
Try to net some cash doing online surveys without wasting too much time.
Find a part time job if you have a lot of time on your hands..
Sell your body (I.e sex If your that kinda person)
donate blood/plasma/marrow (might not pay depending where you're at not sure)
donate sperm or eggs (if your ok of with that idea)