Here is one thats useless but fun,
hold control, option, command , then hit the 8 and you will reverse the colors on your screen.
Not useless. I use it when I visit sites that are black background with white letters. 
...or did QuickLook and Stacks start at 10.5?

Don't know about Stacks, but QuickLook was introduced in 10.5.
Here is one thats useless but fun,
hold control, option, command , then hit the 8 and you will reverse the colors on your screen.
I must be doing something wrong. At least I am unable to get that to work.
Perhaps it's divine retribution for my many (assorted and sordid) sins. Nah...
That keyboard shortcut reverses black and white in Snow Leopard. Apparently, reversing colors has been eliminated, at least from what I see in the Universal Access preference pane.
Harv:
If it doesn't work for you, check in the Keyboard preference pane (Snow Leopard, again) to see if that keyboard shortcut is enabled. In my system, it is disabled by default.
That was it, Jon. Thanks!
And of course, it's most comforting to know, 'tis only moi, and not that retribution thing.