SmokeScreen is a simple privacy tool which allows to conceal what you're doing on a PC with the flick of a mouse.
You can activate the program by moving it to one of the corners of edges of your screen, for instance; rolling the mouse wheel; clicking the middle mouse button, or clicking both the left and right mouse buttons together.
By default your chosen action will minimize all windows. Leaving a blank desktop could look a little suspicious, though, so the program can also display a decoy screen capture which you take at some earlier time, packed with other applications. This won't stand up to close scrutiny (the clock will be wrong, and you can't click or drag anything, as it's just an image), but if someone just gives it a casual glance there shouldn't be any problems.
There are some design issues here. The program claims it always activates when you hit the "~" key, for instance (only on our PC it seemed to be the apostrophe, presumably some kind of key mapping issue). And you can't turn this off.
And SmokeScreen's activation logic appears to be a little strange (or there's a bug, we're not sure which). We could activate the program once via a mouse action, but that was it: it wouldn't do anything else until we closed and restarted it (or pressed the apostrophe key, which annoyingly worked all the time).
The program is seriously flawed, then, but if you just want to protect yourself in a situation where you're not doing much typing (using a browser, say), it may be just about good enough.
If you decide to try SmokeScreen out, though, be aware that it tries to install a browser toolbar. If that's not what you want, pay close attention during setup and clear the relevant checkbox.