Yes, it's everyone's favourite graphics editor, Microsoft Paint.
While looking around the internets, I discovered a number of features in Paint that a lot of people don't know about..
The tertiary colour
Most people know that you can pick a primary and secondary colour in Paint - primary is left-click, secondary is right-click. But did you know there is a tertiary colour controlled by CTRL+click?
In case you didn't guess, this means that you can use the tertiary colour to paint by holding CTRL while click-dragging the cursor in whatever tool.
Fixed lines, rectangles and ellipses
This feature is fairly simple, but there are still a lot of people who don't know about it. Holding down SHIFT while using the ellipse, rectangle or line tool will result in a "regular" shape. That is SHIFT+ellipse produces a perfect circle, rectangle yields a square and line a line at exactly 0 or 45 degrees from the horizontal or vertical (ie. all the cardinal points including NW, SW, NE, SE).
Clone and trail tools
This is a less useful feature that is still quite interesting and not very well-known. Select an area with the freehand or rectangular selection tools, then hold down CTRL or SHIFT and drag the area. CTRL clones the area - a duplicate image is created, much as if you pressed CTRL+C/CTRL+V. SHIFT creates a trail of the area - as if you had continually been pasting images. It certainly could save you a lot of time if you wanted to do this in the first place, and had to do it in Paint for some bizarre reason.
This is a bit glitchy. If you click a certain row of pixels just below the 8x magnification level, you can get 10x magnification.
Apparently this is a removed feature. It's not all that useful considering how much of a pain in the ass it is to get the right pixel row, especially since it makes almost no difference whatsoever.
Anyway, I found these "easter eggs" fairly interesting. More easter eggs can be found at eeggs.com, including the famous Word '97 pinball game. Also, a substantial amount of this article was shamelessly taken from the Wikipedia, although I did rewrite it. Wikipedia also has an article about Paint .NET, which is apparently an open-source program made under Microsoft's guidance.
64k 'net sucks. :-(