I'm very familiar with this phenomenon of doing frivolous things instead of the things on my lists. One thing that has helped me, which I haven't seen mentioned yet, is simply thinking out loud. (Note, I did not say thinking "loudly" but "out loud", just loud enough for you to hear yourself -- in the same manner as many people sub-vocalize as they read.)
I've found this practice to be of immense help when making decisions about what to do off my lists, when organizing my brainstorming notes, and when processing my inbox. It's also good for pulling me out of the "busy trap." When I start to get an uneasy feeling that I'm not making the best use of my time, I'll often start a conversation with myself. It may sound strange, but it really does help me get unstuck quickly.