If you're tired of discovering that you've turned caps lock on accidentally after you're halfway through a sentence typing in all caps, CaPNotifier is a tiny Windows utility that will pop up a discreet notification when you toggle caps, num lock or scroll lock on or off.
After the alert appears, it fades away after a second or two and lets you continue working. It may sound annoying at first, but you get used to it quickly and the reminder isn't out of place at all. CaPNotifier reminds me of previously mentioned CapSee, another great utility that does a similar job in Mac OS. The app can also alert you when you press shift, control or alt, but those options are off by default.