There's an interesting utility the magazine highlighted recently which basically acts as a "short term" protection for an existing open application window from onlookers. It allows one to run a screensaver which support "preview" mode WITHIN an existing open window application.
Possible uses is that you're currently working on a something in Quicken/financial app and you just need to step out for a little while but do not want to close down the application. This allows one to protect the window content but still allow the use of the computer. Once an app is "locked" the window can not be moved, closed, minimized or maximized.
Wouldn't the use of a screensaver's preview mode to an application window be a great idea if used in some of the utilites in Donationcoder such as DimSaver? I mention DimSaver since I think it would be neat when running as batch file that runs a long time (such my compression archiving for backups) but you want to keep track of the screen messages as well as not having someone terminating it.