Why is it that all webapps have to be 'fun' or 'social' applications these days? I wrote some software (as a webapp) that I think is pretty useful, but has only the barest and most rudimentary social networking features. I showed it to a co-worker whose first response was "cool". His second response, a few days later was, "I'm going to build a copy of your program, only I'm going to make it focus on the social and sharing aspect. I hope you don't mind."
Now, on one hand, I'm not really offended, since my app is just a clone of an existing (but unavailable to me) app. On the other hand, I'm pretty offended that to this guy, software isn't good unless you can socialize through it. I'll admit that there is a natural social aspect that comes out of the idea, but whatever happened to solitary software that just helps you be productive and organized? Why the heck isn't there a simple web-based address book out there? That said, I applaud mint.com and their decidedly non-social approach to webapps.
Right now everyone is talking about facebook, social software, and what have you. But most of these sites aren't making any money, and they never will. It's basically a really crowded market with no clear income model unless you're really big.
Find a niche that hasn't been exploited and create software that solves a problem in that niche. B2B is probably the best place to look - if you can come up with a piece of siftware that can either save a company money or make them money they will be happy to pay.
If you have ever seen SAP's implementations of ERP systems you will know that the B2B software out there is totally crap, and that it should be possible to come up with something better. And there are real companies willing to pay real money for your software.
There are plenty of people and companies and people that want and will pay for useful software, you just don't read about them on digg or reddit because they aren't sexy and cool.