I use the Flock browser as my main work (and home) environment. I like the way it brings gmail. facebook, and my RSS aggregator into the same in-browser environment. I could do other stuff but that is enough to be getting on with. One click and I can look through folks' status on Facebook. I can see who has added new media and show it handily in a nicely integrated media bar. I like the way it tells me if I have new mail and the RSS aggregator works as well as anything I have used (which is not a lot).
However, I am wondering if I might need to dispense with it as my main browser. As I am somebody who saves my will-power for important issues it gives me too many opportunities for distraction!