Valve Adds Steam Tags

Service feature adds a new way to shop for games and software
Valve sent over a press release announcing the launch of user-defined "Tagging" of Steam products, a feature that gives Steam customers the ability to "Tag" any title with genres, themes, attributes, or any other term or phrase. The most popular tags on any given product will be surfaced on said product's Steam page and allow users to easily find other products associated with that same tag.
Steam Tags is currently in beta testing.