My most-productive weeks are the ones where I sit down on Sunday night or Monday morning and decide what I should be working on each day of the upcoming week. I like to set out two or three “most important tasks” (MITs) for each day. If I get those things done, I feel good, even if they are the only things I accomplish that day.
You can do this sort of work planning on anything, from a scrap of paper to Outlook, but I have fallen in love with TeuxDeux (pronounced “to do”), a “simple, design-y to-do app.” It has no bells and whistles, just a beautifully simple interface and the tools you need to rough out your days.
Also, the intro video rocks: