- Youth and Culture - basically a bunch of social networking sites that are targeted at the younger crowd. If they succeed, they will bring together a juicy group of targets for retailers and marketers. But brands will have to be careful how they approach these sites - if you think there was an uproar over Beacon, think about the privacy implications of advertising or diving in to sites that cater to tweens. That's going to be laden with a lot more landmines.
- Memes and News - the theme here is filtering or aggregating content in some way or another so that it's easier for people to wade through - either by creating a niche of some kind ("news about your friends instead of news by your friends"), or using the crowd to surface the most popular stories from within a world of "TMI". Product reviews kind of do the same thing, but ultimately I can see this kind of functionality melding in with another category - "Vertical Social Networks" - one of which creates a social network around shopping and fashion.
- Finance and Statistics - a bunch of sites that put analytics around either information on the web that relates to people or topics, or information specifically about a person or topic. For retailers, this could be turned inward to employees (especially frontline employees where it's hard to really do a thorough check on the person before you hire them), or turned outward as a service to customers. Safeway's FoodFlex program is a good example based on "closed" data (Safeway's clubcard purchases - Safeway offers to analyze the nutritional value of your past purchases and recommend ways to create a healthier diet), but as more of people's lives end up captured online, someone's going to think of a way to take advantage of it - including purchase or shopping/browsing history.
Retailers have never been keen to be on the cutting edge of technology adoption. It's one of RSR's fundamental "Paradoxes of Retail" that retailers must manage a heavy load of legacy technology infrastructure at the center of their business while consumers are adopting technology at an unprecedented rate - and forcing retailers to speed up or be left behind. The TechCrunch50, to me, shows that the pace of change isn't letting up at all.