Useful for url-shortened links on Twitter which open up to "You're missing Adobe Flash Player 10 Plugin..."
If you haven't already, enable the Develop menu in Safari: Preferences > Advanced, check "Show Develop menu in menu bar".
Assuming you've got Chrome installed, navigate to Safari's "Develop > Open Page With" menu, and take a note of the exact menu title for Chrome. For example, "Google Chrome (21.0.1180.57)".
Open Keyboard Preferences and under the Keyboard Shortcuts tab, add a new shortcut to Application Shortcuts. Select Safari as the Application. Enter the Menu Title you noted above (minus the quotation marks). Finally, type your shortcut of choice - cmd-shift-O, for example.
Obviously this will break when Chrome updates, but change the build number in your shortcut, and you're all set.