I have been using the free 2GB Dropbox account to store my SSH keys for our servers. Along with my mutt and other configuration files. The best part of Dropbox on Linux is being able to symlink things into the Dropbox directory to allow me to have the same configurations on all the various computers I use.
Basically what I do is have a .ssh_keys directory in my main computer’s home directory which I symlink in my Dropbox directory. Then on other computers I create a:
ln -s /home/myuser/Dropbox/.ssh_keys /home/myuser/.ssh_keys
I do the same with my .muttrc and any other configs I want to use. I even keep my wallpapers in the Dropbox folder where my awesome config file randomly loads one using:
awsetbg -f -r /home/myuser/Dropbox/wallpapers/