http://www.bitcoinplus.com/generate

 You must have Java installed to use the bitcoin generator.
If your browser asks you to run the applet, or to install Java, say yes.
Waiting for Java applet to load...
Step 1: Click "Start Generating"
Step 2: Wait while your computer works (leave this page open)
Step 3: Earn bitcoin

It's that easy. Want the explanation? Read how bitcoin works, but click "Start Generating" first so you'll earn bitcoin while you read.