I want to merge multiple rss feeds into a single feed, removing any duplicates. Specifically, I'm interested in merging the feeds for the tags I'm interested in.
[A quick search turned up some promising links, which I don't have time to visit at the moment]
Broadly speaking, the ideal would be a reader that would list all the available tags on the site and toggle them on and off, allowing me to explore what's available, keep track of questions I've visited, new answers on interesting feeds, etc, etc . . . though I don't suppose such a things exists right now.
As I randomly explore the site and see questions I think are interesting, I inevitably find "oh yes, that one looked interesting a couple days ago when I read it the first time, and hasn't been updated since". It would be much nicer if my machine would keep track of such deails for me :)
Update: You can now use "and", "or", and "not" to combine multiple tags into a single feed: Tags AND Tags OR Tags