Keep in mind, this relies heavily on conditional formatting to tell you how you're doing, so it only works in Microsoft Excel 2007. If there's interest, I can make a copy available that'll work on older versions, too. 

This sheet keeps track of your daily word count, the percentage completed, your average words per day and will tell you, if you fall behind, or get ahead, how much you can adjust your daily word counts and still reach your goal. The colors and symbols on the sheet adjust depending on how well (or how not well) you're doing. I'm shooting for 60,000 instead of NaNoWriMo's 50,000 -- so the monthly goal is customizeable, too. Just pop in what ever word count you're aiming for. The second sheet is the same, I just loaded it with some sample data so you can get an idea of what things will look like as you go through the month.

Good luck!