A good way to get free cash by doing things you already do is to shop online through sponsored links. You can do this through several different sites, and you can compare cashback rates to get the most money back for your time.
Check out my Get Paid to Click post for info about companies like MyPoints and InboxDollars. These sites do paid shopping, and the cashback rates change from time to time for various websites.
Shop at Home is another great site. Shop through their links and you receive a percentage back on whatever you spent. Cashout comes when you reach $20. Refer and friend and get $5 added to your account!