Lets say you are running something over VPN,
and VPN suddenly fails, then this will kill the app you dont want to connect via the normal interface.

Its just a small ruby script you can put into e.g. /usr/bin/

vpn-fuse VpnName 'killall secret-app'
vpn-fuse BankNetwork 'killall bank-client'
vpn-fuse iPredator 'killall transmission-gtk'
...

so far only tested on Ubuntu…

vpn-fuse