This was completely unclear to me from your site, although having re-visited it's less unclear. It's certainly unclear what tags exist, how you deal with synonyms, how I edit my tags, whether I can change the order of filter-out and filter-in, and so on.
You need a much better interface to the editing of the tag-based filters.
And content.
Another question - suppose there's an item about an algorithm in PHP. How do I know it will get given the "algorithm" tag? How are tags assigned/chosen?