I love my Mac, and I love OS X. I’m not afraid to admit it. That being said, my Mac doesn’t do a great job of keeping me up to date on, well, the date.
Sure you can customize the Date & Time display in the upper right-hand corner to include today’s date, but that doesn’t help me when I need to quickly find out what next Wednesday’s date is (and it doesn’t help that even with the day and date display I often go entire Tuesdays thinking it is, in fact, Wednesday).
I need constant reminding as to what day of the week it is, and how the month is shaping up, which is why I love Machine Codex's free DateLine. This tiny utility only does one thing: displays the days of the current month in a line. You can have the timeline act like any other window, have it float above all other windows, or anchor itself to your Desktop (which is what I do). It won’t keep track of your appointments or tell you what holidays are coming up but you can set it to open iCal to the corresponding date when you click on it in the time line.
I know there are lots of other apps out there that aim to solve very similar problems, in many different ways, but the simplicity of DateLine can’t be beat (for my money).