Showoff is a simple service that lets you use your local computer as a file server over the Internet. You install the software (a Ruby gem), specify a folder or file using the "Share" command and then get a URL for sharing the location - ie, https://you.showoff.io. It's only available for Unix-based operating systems like OSX and Linux. There is now Windows version, but it might be possible to get it working with Cygwin. Update: Showoff requires a work Web server already be running.
PageKite offers a similar service (this one based on Python), and has open-sourced its code. It is available for Windows, OSX and Linux.
From the Showoff website, here are a few possible uses:
- Share your showoff url for a locally run dev server to get some quick feedback from clients or other developers
- Test your locally run dev server with a real SSL certificate (great for pesky IE SSL bugs)
- Develop and test against APIs that require callback URLs accesible on the public Internet.
- Develop and test mobile applications against locally run servers.
Showoff charges $1 a day, or $5 a month for unlimited use. PageKite is free for up to 1GB of transfer, and costs $1.50 per GB after that, with discounts for purchasing larger amounts of bandwidth. Update: PageKite lead developer Bjarni Rúnar Einarsson comments that the free quota is 2.5GB, not 1GB.
This thread on Hacker News has a few comments explaining how to set something like this up yourself for free.