The search, Web2.0, blogging, social networking and now online television.
There are two kinds of innovation happening on the internet today. The first kind are the ones which are redefining the internet, and the second kind build over the first kind. Unlike traditionally research and innovation, its not the idea but the implementation and execution which makes or breaks a production or service in todays world.
As a hobby for the last few years I've played around with quite a few ideas to understand the implementation and execution complications involved in bringing ideas to life. I wrote a internet feed crawler 2 years ago, created a personalized feed reader preference detection engine using bayesian algorithm, created a IP/networking debugging tool called huntip.net, a digg like social news publication site called zoppr... and the latest experiment I had with was a service called flagthis . In my other life (at my real job) I kicked off a search product based on lucene with a fullblown Ajax interface using GWT 3.0.
I'll be on the lookout for the next interesting idea to implement... and experiment with. Let me know if you have something interesting to share.