I admit that I am something of a klutz. I frequently have overlapping windows open on my busy desktop and, while trying to reduce the confusion, accidentally click the close box on a Web browser or some other window, losing whatever was in there. NoClose is a simple, free utility that disables the close box, saving you from yourself.
A keyboard shortcut easily toggles the top-right close button on or off in all windows, programs, and folders. Even when disabled, though, you can still close windows with the File menu.
NoClose is admittedly a one-trick pony that solves a pretty narrow problem. If you don't have fat fingers and never shout "Noooo!!!!" after closing some obscure folder on your hard drive that it'll take you another 10 minutes to locate again, then keep moving, there's nothing to see here. But if that sounds like a problem you've experienced, give NoClose a shot.
And speaking of "Noooo!!!" moments, don't miss Lazarus, a fantastic Firefox extension that recovers lost form data.