Chris -- one approach to keywords is to relate them to actual page content and not overall site content.

Search engines have the job of finding relevant results to search queries. Try to work with them instead of trying to fool them. It is probable that you'd rank higher with keywords that are relevant to actual content -- and perhaps rank lower because you put a bunch of keywords that aren't on the page. Each page in your site can have its own unique list of keywords that relates specifically to the content of the particular pages.

Regards, Ross