An idea: store a FOAF file alongside a person's weblog (as TyePad will do automatically), and include in that file a pointer to that weblog's search engine, which would return results in a standard (or self-describing) format when requested by a spider. You could also include a pointer to a search engine for that person's store of reviews, or photos, or anything else.
By also including in the FOAF file pointers to other, recommended weblogs, a spider grabbing the first file would then be able follow those pointers to continue searching through this web of trust, gathering up opinions about books or music, relevant blog posts, items for sale, etc.