Savable custom filters

I think it would be a nice feature to have something like custom categories that users can create themselves.

For example a filter for some "light reading on the road":
 * Reading time < 5 minutes.
 * Tags: news.

Some of the criteria that should be included in the filters:
 * Reading time.
 * Tags.
 * Domain?
 * Search string?
 * Favorite?