People who use multiple browsers regularly: What are y'all doing in each?

To piggyback off the "Best Browser for Mac" post in here: I saw a lot of people respond to that by indicating they use several browsers on a regular basis. Not just one at work and one on their home Macs, but multiple browsers open simultaneously, or at least several they switch between on a regular basis. This is so foreign to the apparently casual way I drive on the Information Superhighway that I gotta know: What are y'all doing that requires this setup? I'm fascinated to find out; I really don't mean this in a derogatory way. What sort of work are you doing, and how do you find it helps to have several open, or several in a regular rotation? Do my solo-browser surfing habits clock me as a n00b?