From a command prompt, do ssh -D 8080 user@host to some host you can ssh to, that you do trust.
Then go to your network settings, and set a SOCKS proxy at localhost:8080
Now all your SOCKS aware applications, like your web browser, mail client, and IM client, will tunnel their traffic to that machine, and the local network and local outbound firewall can only see a single opaque ssh connection.
