I'm interested/ been heavily exploring:
PCs in the living room (everything from custom linux distro, XBMC Live modified, and windows 7). 140 million HDTVs sold in 2009 alone, hardware is getting cheaper, and content is readily available.
Education space. ie- how do we provide easy access to all the materials that exist out there? My hypothesis: everything we could ever want to learn exists already on the net or can be taught to us by a person we can be connected with in seconds. How do we easily organize it? think more of a directory than a search engine.
Bringing local businesses into the 21st century. Most don't have a website and still use yellow pages. The existing solutions out there suck and are filled with slime.
Email newsletters. Why not create the weblogs inc of newsletters? Look at what thrillist, dailycandy, etc. have done. Create a network of these around a plethora of wide open niches along with building a strong advertising platform for email newsletters (it doesn't exist yet).
Human powered purchasing decisions. How do we help people know what to buy with specific criteria that transcends checkboxes and a search engine? Something human powered is the way to go about it. As geeks, I'm sure you're constantly asked- what phone should I get for price x, features y, etc. Purchases such as these are expensive and spending a few bucks more to get a personalized recommendation would be worth it.