targeted posts via radio button and user preferences?

[sross]

Here's the idea:

Let's say there is a photography site with 20 forums. it has 2,000 members with varying interest in the forums. I would like each post (when the user is creating it) to have a radio button selection that says:

Choose a type for this post:

o traditional photography
o hybrid photography
o digital photography
o off-topic

The user clicks on digital photography and makes his post in one of the forums. Another user in the forums has gone into his profile and has 4 options:

You want to view:

o traditional photography
o hybrid photography
o digital photography
o off-topic

The user selects all options but digital photography. So now, when the user is browsing all forums, he will not see any posts which have been tagged as "digital photography".

Make sense? I would LOVE this hack or info on it if it already exists! Thanks