a9.com search enhancement--related to folksonomy?

http://a9.com -- a search service offerred by Amazon and based on Google technology has added a new service "openSearch" columns to it's search interface. In addition to the regular tabs for additional searches that a9.com offers (web, books, movies, reference...) you can now add custom tabs for any "openSearch" service.

What is OpenSearch?

"OpenSearch is a collection of technologies, all built on top of popular open standards, to allow content providers to publish their search results in a format suitable for syndication....OpenSearch is not a search engine—it is a way for search engines to publish their search results in a standard and accessible format."
from http://opensearch.a9.com/

Add your own custom column to A9.com and share it, you can make it an optional tab in the a9.com search interface.

n.b., you have to be signed into a9.com to add more than one tab to your results screen.