I spoke with Toluu developer Caleb Elston yesterday evening, and he told me "tagging has been the most requested feature" since Toluu launched back in March. By adding tagging to the vast majority of feeds, and letting users add new tags to feeds, he hopes this will improve users' ability to discover new content. So far, he told me, more than 35,000 tags have been added, even before it's reached the hands of the service's user base.
Beginning today, every feed in Toluu will feature a "tag tab", which will show existing tags for that feed, or let users add new ones. Smartly, the service remembers tags you have made in the past, and those will auto-populate, much like the behavior on Del.icio.us.
Also starting today, you can view any other Toluu user's list of tags most frequently subscribed to, in addition to their entire feed list, with a feature called "Profile Top Tags". Now, I can see if you commonly read up on Apple and Google, like startups or social media, and can traverse your tag cloud to see which feeds match those tags.
As the tagging engine hasn't hit the public market, it's clear there is more work to be done. Toluu leverages the categorization users place feeds in during OPML import, and while Caleb said Toluu scrubs for odd tags, I've seen a number of feeds with tags that look like they are the result of a single individual.
So far, Toluu hasn't made too many efforts to become a destination site. Instead, it's a utility that helps you find better RSS feeds, and learn what your friends are reading. But with the addition of tags, users may just be sticking around a little bit longer to fill out their RSS subscription to do list. If you still don't have a Toluu invite, which is nuts, you just need to ask me for one by leaving your e-mail address in the comments, or sending me a note to firstname.lastname@example.org. You can find my account here: http://www.toluu.com/louisgray/