I may have commented on how great NetNewsWire is a couple of times before (1, 2) but I have to do it again.  If you have the full version of NetNewsWire (as opposed to NetNewsWire Lite), you can easily create and subscribe Feedster searches using File->New Special Subscription->Search Engine.  There’s a range of search engines you can choose from and a bunch of other options in the New Special Subscription that may be useful as well.

The feedster search is particularly nice for me though as previously the only RSS search engine I’d managed to get to work reliably was Technorati and it’s results were really disappointing.  Now I just type in the search term and it works seamlessly every time.

Those who think tags are actually useful will be pleased to know that one of the special subscription options is “Tag…” and it can search Technorati, Flickr and Delicious tags.