Is there a table of BMW engine codes?

I can tell my E36s from my E46s, but I have no idea what all the engine codes mean (an M20 engine vs an M60 engine) etc.
Is there a table somewhere which describes what engine is which?

Here is a good source: http://www.unixnerd.demon.co.uk/enumber.html

Ahhh. Thank you. It is a bit clearer now. There are some cross-overs such as how M60 designates both a 1992 V8 as well as a 1978 straight 6 (aka M20).

There is a fantastic amount of info and external links in
http://www.wikipedia.org

Here is a good list but it is somewhat dated:
http://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_Designation_faq.htm

And:
http://www.bimmerforums.com/engine_faq/