My “Open With” menu option was getting way out of hand and I can never remember the command to clean it up so, I created this Alfred 2 workflow.
Once installed all you need to do is type
cleanupow into Alfred and hit enter. Open With will be rebuilt and Finder will relaunch.
You can get the workflow on GitHub. If anyone wants to, they can help pretty it up by designing an icon.
Update: Apple have fixed this bug in El Capitan, so I have removed it from GitHub