Key-ncognito
This is a Chrome extension which allows opening links in incognito mode using the key-combination Meta + Alt with a Click on links. The key combination can be changed via the settings page.
The Meta key could be the Command Key (on Mac), the Win Key (on Windows), Context/Menu Key (on Linux) or any other system determined key. The Alt key is also called Option key on Macs.
Available as a Chrome extension in the Chrome web-store.
