Modules|Themes can be tagged by the owner of the module. And will improve search results:
http://en.wikipedia.org/wiki/Tag_cloud

Example: Module "Views" (tags, display, content, Dev, Beta, etc...) and filtered by it's version v6, v7 etc.
Drupal-Association itself is using this feature but it is not found on drupal.org.
Theme: Tags(Colors, Columns, Dev, Beta, HTML5 etc...)
I think you all understand well what I'm talking about so vote. :)

(Click here to vote on Drupal-Association)