KZero is a British “virtual worlds consultancy.” Unlike many people claiming this title they actually seem to be the real deal. They are not, as far as I can see, aligned to any particular world, and they are most definitely not part of the flotsam and jetsam that bobs around the good ship Second Life.

Their site announces that

We are specialists in connecting real worlds brands and companies with the residents and environments of virtual worlds. Since 2006 we have been examining and assessing the drivers affecting virtual world adoption and the marketing opportunities presented by the metaverse.

The material on the site seems to back up this claim.

They have a range of charts detailing hundreds of virtual worlds (many of which I had never even heard of) in terms of their type, their demographics, their number of registered users, and more.

They also have an interesting range of case studies. And a blog that is well worth subscribing to.