Yesterday I was looking through free applications for the iPhone and came across something called StitchMinder, it had a pictures of a ball of yarn in the little button and I did a little dance for the intersection of knitting and technology.
Doing a hat with four sets of decreases? Label all the sections Decrease Row and tap after each decrease. You'll be able to see how many you've done. Set all the sections to count in descending order, and set the start number to the number you need to do, then tap away as you knit and you'll be counting down instead of up, which can be handy to see how much you have left (or simply for motivation). For each counting area you can choose a label - Rows Completed, Pattern Row, Pattern Repeats, Increase Row, Increase Repeat, Decrease Row, Decrease Repeat - so you can keep track of different areas of the pattern on the same screen. You don't lose your numbers if you close the application, turn off the phone or set it to sleep mode.