The six month window that Google implemented to prevent link buyers to fool the engine into giving page rank to sites that they felt didn't deserve it. Coincidentally, I am now in it since I just purchased my new domain on July 27 and I am in the sandbox as well. I want out. Any advice?
If you build backlinks at anything other than a snails pace than you get put in the sandbox. While you're in it if you keep building backlinks than you'll emerge stronger than before. It's said to last 3 months. But you're site may just be dancing.
Just build backlinks to your site daily. As long as you provide link juice to your site, you should be kept out of the sandbox.