CPM

If a certain banner advertising venture costs $5 CPM, then your ad will be displayed 1000 times for every $5 you drop on it.

Why it's CPM I may never know, it probably comes from the Roman Numeral M which means 1000. However, why this is the standard boggles my mind, I would think they'd use something more mainstream like Thousand or even Kilo (and yes I know that Kilobyte != 1000. shut up, you nerd.).

WPM: Words Per Minute
CPM: Characters Per Minute

CPM is a convention used in measuring typing speed. Usually, CPM is raw characters per minute, and WPM (Words Per Minute) is derived by dividing your CPM value by the average length of the word in your test (usually 4-6).

CPM is a better indicator of raw typing speed, but is not particularly good at telling you whether or not you can handle typing actual sentences or not. Things usually get a lot trickier for touch typists when they have to handle numbers, quotations, special characters, and mixed case.

There is, of course, a more detailed write-up available on WPM.