Creating dynamically filtered layers using Tilestache/Mapnik?

I'm using Tilestache to generate two layers with the mapnik and mapnik grid providers, and it's working great!

However, I want users to be able to filter the data over many (more than ten) dimensions, and only show the features that match the user's filters. Creating a mapnik and mapnik grid layer for each of these dimensions--and each new one that comes up--seems like the wrong way to do this. And there are too many features to simply use GeoJSON.

Is there a way to do this filtering dynamically?

Intuitively, I'd like to pass parameters via GET request to Tilestache, which then passes the parameters along to the layers' providers, which tweak their queries.