I've been thinking about this a lot too.
Theres survey sites that you can make some extra money on.
I use Pinecone Research, each survey you complete gets you $5.
You can also sell your things on Ebay, craigslist, and kijiji.
And if your crafty, make and sell things on Etsy.
If you know any older people, you can do their shopping and clean their houses.
Walk dogs.
Babysit.

When doing any of these things make sure your doing them safely and always carry a cell phone and tell people were your going. You can also team up with a friend. Hope this helps.