Jeff Jarvis has a spot on post about using tags for information about people.

People tagging creates a marketplace by matching content against people's needs and interests. In the case of jobs - a tagged job requirement matched against a tagged resume.

As it happens I will be launching a new product soon that includes some of these elements. I want to eventually take tagging one step further and use it to create any type of metadata, allowing people to create tag/value pairs in their own namespace and create RSS modules on the fly.

The premise of this is that at the moment the name portion of the name/value pair in a tag is 'category' i.e. if you tag something as a 'resume' you are saying 'category=resume'.

What is interesting is when you allow people to invent their own 'name' portions of the tag. e.g. 'category=sushi_restaurant location=new_york'. That's what I'm working on.