We've outlined a few things you can do when Dropbox goes down, but if you want to take a more extreme approach you can roll your own Dropbox-like syncing and backup service with some open-source software.
Tech hacking blog Fak3r outlines the process and what you'll need:
- At least two machines, one to be the server and one to be the client
- Some open source software: OpenSSH, rsync and lsyncd
The process involves some work and command line know-how, but it's all pretty straightforward. We think Dropbox is awesome, but if you want a DIY method you should definitely check out Fak3r's instructions.