Our pages can each have many tags, e.g 'football', 'sms', 'nsfw', etc.. wich we would like to track in google analytics.

We're already tracking things like category using google analytics custom variables. We've used three of the five available slots so far.

How can we track tags the same way? If we just mush them all together - e.g. 'football, sms, nsfw' then can we track the ones that are tagged 'football'? What's the right way to track multi-valued page attributes using custom variables?