Update: don't fancy compiling/testing the code? See the short video clip.
I found one piece of code which I wrote a very long long time ago.
Remember the original Quake? When you submerge, the software renderer performs a simple but interesting effect. The view is somehow warped periodically. It turned out that you just need only few lines of code to achieve such effect. Just see the code if you're curious.
Of course, looking only at the above screenshot is not enough. You must see it in action.