Thanks for bringing HTTPS up, that's another good use-case for Showoff. If you're developing a web app that needs to be tested with HTTPS and don't want to mess with creating a self-signed cert, Showoff can help you out.

It's also really nice for testing web hooks or API callback URLs against a local web server (e.g. ecommerce sites with IPN, &c). If you sign up for an unlimited account, you can choose a permanent URL to use for your tunnel (e.g. "my-name.showoff.io").