hi stief,

Myster does something else, because it just puts the files into cathegories (more exactly: The user has to do it) and searches only in the cathegory, which the User selects.

Every one of those cathegories optimizes its own hostlist independently.

In Gnutella something more simple would be possible: Being closer to those with the same interests.

If your UP connects mostly to UPs with similar interest, you are more likely to find interesting files, because you reach those hosts more easily.