I have been working on the idea of cross indexing all the internet social data available. For example, there is no easy way to match your Foursquare check ins to your Yelp reviews. If you matched that data, your Yelp review will be more authoritative. Same thing for expending patters. If you could match a credit card purchase with a review of an item, your review will carry more weight and the vendor will be more interested in contacting you to help soothe any problems.
How about matching people on real compatibility? Matching them based on their movie taste (that information is in Netflix), what type of restaurants they go to (Yelp, Foursquare), what they listen too (based on their iTunes account), etc. The best part of this matching is that the user does not have to enter any information, just give the system access to their Netflix, Yelp, Foursquare and iTunes accounts via oAuth.
How about a restaurant recommendation service based on what people with your similar social profile (taken from Netflix, Yelp, Foursquare, Yodlee, etc) likes? It will be the Pandora of restaurant recommendations.
How about message boards where only users with a certified connection to the topic can post to? I enjoy and practice martial arts. I would love a board where all the poster are certified to actually belong to a martial arts gym. That is easy to do if everybody shares their credit card data.
How about something even more radical? A site for patients where only people with a certified connection to a topic can post in it. For example, you can only post in the disease X board, if your medical record indicates you have or have had the disease. The system can do all these verifications if you provide it your Google Health medical record.
I am starting to believe that there are new set of services that can make our lives much easier if we just cross reference and share all our online social data with smart systems.