First thing you'll want to do is ssh into your server but this time we're going to pass a -R flag and a port number. That flag "Specifies that the given port on the remote (server) host is to be forwarded to the given host and port on the local side." Basically a reverse tunnel..
ssh -R 19999:localhost:22 email@example.com
Once you're in, you can ssh back to localhost:
ssh localhost -p 19999
or copy a file down:
scp -P19999 YOUR_FILE youruser@localhost:/home/youruser/
And that is all there is to it! Credit due to HowTo Forge for pointing the way on this. They've got a bit more on the topic that you can read about here.