I have a big problem with launching firefox everytime I have 20 seconds of downtime (like when I'm building a big solution, or I'm waiting for a large file to load in my application). By the time I look at whatever site I decide to go to, it sucks up more than the 20 seconds of downtime and costs me a lot of time "context switching".

Something that has helped me with this problem: I took firefox off of my quick launch bar and put it on the desktop. I now have to be much more deliberate in when I actually need to use the "tubes".