Today I wrote a quick, basic OpenSearch module for Drupal. It implements the Amazon-originating spec for syndication and aggregation of search results.

The interesting part is that OpenSearch builds upon RSS and Atom, which means that the resulting feeds can be used in any news reader. Of course, an OpenSearch-aware reader can interpret the extra information that is present (total number of results, other search pages, search URL syntax, ...).

I've installed the module on Acko.net, so you can give it a try here: OpenSearch description file (XML) Search results for the query "Drupal" (RSS)

The module will be available on drupal.org as soon as CVS Contrib is repackaged in a couple of hours, though it will require Drupal CVS HEAD or 4.7-HEAD to work.