If the search method behind phpBB wasn't so damn awful the idea of personalised filter-forums would be feasable. I find even the 'next-generation'
(heh) versions of IPB and VB to be horribly lacking in their search capabilities.. haven't had much of a play around with phpBB 2.1 though.
My thought is that the limits of server resources would rule this method out for larger forums, which can struggle with the CPU requirements of a regular forum as it is. When a post is made, it is broken down into individual words and added to the search list
(saying 'individual' crops up in post #12545) and then 2/3/4 word phrases need storing in similar gigantic lists, and some form of relevency calculation needs to be made. The first part is implimented already, the second two still need to be added to this forum at least to get it running properly. You would then have to compare the new post against everyones manufactured filters and drop it into the matching users to-read list, similar to the current read history that is stored.
It's an interesting idea, but I won't claim to have the time or knowledge at the moment
![Cheesy](/amforum/Smileys/classic/cheesy.gif)