I have been a Feedster subscriber for months now — just punch in the RSS feed for a search query, and your aggregator will return to you any results for that query. It’s a very handy way of monitoring what’s being said out in the blogosphere outside of the blogs you normally monitor.
Courtesy of Lilia (two in a week! she’s on a roll!), I now have another service that provides RSS feeds of its search results: Waypath. The Waypath page explains how to do it here. Very straightforward, and very helpful. So far, there’s been little overlap between what I’ve seen at the two sites.
Anyone else aware of other RSS-enabled search engines?