At work, I use synergy to control two computers with the same mouse and keyboard. My main desktop (skynet) has two monitors - generally one for Firefox and one for my terminals - and my secondary machine (mithrandir), a third monitor on my desk, handles email and IM. The only real problem I’ve had with this is mailto: links, which obviously don’t work since my browser and mail client are on different computers.
Getting cross-machine mailto links to work isn’t all that difficult, at least with thunderbird which accepts a “-compose” command line argument. First, get passwordless pubkey SSH authentication setup from the web browser machine to the mail client machine. Then set your mailto handler/mail client to a shell script in your path. Finally, fill the script in with something like:
#!/bin/bash ssh mithrandir "export DISPLAY=:0.0 && thunderbird -compose '$@'"
This first sets the DISPLAY environment variable so thunderbird can open a window in the already-running X session, then invokes thunderbird passing it the mailto: link as an argument to -compose. Note the single quotes which prevent spaces in the link from breaking things.