Okay, I guess I wasn't clear. You can't just go and invent new keywords for those entries - you're restricted to the ones listed in the
documentation (minus 'calendar', as mentioned above).
For custom entries, you have two options: Either hard-code the entry in header.thtml or use the 'custom' entry and have some code in lib-custom.php that replaces it with the link you want. The lib-custom.php that ships with Geeklog has some sample code.
Actually, another option would be to use a static page (like we do with "Support" here an geeklog.net). Check the "Add to menu" checkbox and enter a label for the menu. Whether that is an option for you depends on what you want that "contact" link to do.
bye, Dirk