How can I remap the "`" key to "Esc"
KeyRemap4MacBook

A preference pane with currently about 1500 remapping options. Includes Backquote(`) to Escape and Escape to Backquote(`).



Ukelele

You could create a custom .keylayout like this:



Esc on the layout above worked with all of the things I tested:


OS X UI actions like canceling a dialog and exiting full screen
On some websites with keyboard navigation like Google Search
As a meta key in Terminal.app


Modifying special keys from a .keylayout usually results in some unexpected issues though.