Here is a service I would sign up for in a heartbeat: I tell you the authors and musicians I follow, and you notify me when they release something new.

You don’t have to do fancy algorithmic guessing at my interests: there are plenty of artists I enjoy but who I don’t follow obsessively. This is for the few that I want to preorder; for the achingly slow release of new books in a series; for beloved books coming back into print; for the band that doesn’t exist any more but that occasionally gets back together to produce a live album with some old offcuts thrown in.

On a related note: The biggest problem with recommendation systems like Amazon’s and eMusic’s is that they only see what Amazon or eMusic have sold you. They work better the more you centralise your purchasing, which fits Amazon’s interests perfectly but is not something I’m very comfortable with. LibraryThing, on the other hand, has recommendations based on what I own (regardless of where it came from); they’re generally spot-on, which means they don’t generally tell me anything I didn’t know. Unfortunately, this kind of data-mining (based on comparisons with what other people own) can’t anticipate that you will enjoy a new release by a favourite author: it has to wait for other people to start owning it to see whether people with similar tastes have it more often than people with dissimilar tastes.

(LibraryThing also has the UnSuggester, which uses similar statistics but looks for books that occur less frequently than expected in similar libraries. Looking at titles it seems to be pretty good: Shopaholic Ties the Knot (a sequel to Confessions of a Shopaholic) sounds rather ghastly, as does The Purpose-Driven Church: Growth without compromising your message & mission. On the other hand I am part of a presumably rather small potential market for Herman Cappelen’s Insensitive Semantics, and Systematic Theology sounds like the kind of theology I would be reading if I were reading theology. Given the amount of sf and fantasy I read, it’s plain amusing to see Eragon in that list.)