The less I use my mouse, the happier my hands are, and as a bonus, once you have these committed to finger memory, they seem to make everything faster.
I'm going to start off the list by focusing on some key combos that maybe aren't as well known, as they have been carried over from the Linux Emacs editor (which I'm only vaguely familiar with). I find these particularly useful because they allow the hands to remain in the standard keyboard position without having to reach for the arrow keys.
These shortcuts work in the majority of Mac applications. However, be careful when using any cursor moving shortcuts in a web browser, as browsers often default to other shortcuts and you can easily loose what you've been typing. I'm not covering the more obvious ones, like Apple + S = Save, and such (however, you might now know that Apple + D = Don't Save). Those you can pick up just by looking at the menus, as most have the shortcut right next to the menu option. Also, here's a full page of the "official" Apple keyboard shortcuts. For the shortcuts I find most handy, I write them on my shortcut sheet, which I keep on my desk. Here are some of them:
|Ctrl + d||Delete character to right|
|Ctrl + k||Kill to end of line|
|Ctrl + p||uP a line|
|Ctrl + n||Next line|
|Ctrl + a||beginning of line
(like beginning of alphabet)
|Ctrl + e||End of line|
|Ctrl + b||Back 1 character|
|Ctrl + f||Forward 1 character|
The Less Obscure
|Apple + arrow right||end of line|
|Apple + arrow left||beginning of line|
|Option + arrow right||right 1 word|
|Option + arrow left||left 1 word|
|Option + delete (small)||Delete word to right|
|Option + delete (big)||Delete word to left|
|Apple + l||Put cursor in Location bar
(that's a lowercase L)
|Apple + k||Put cursor in search bar|
|Apple + t||new Tab|
|Option + Apple + arrow left or right||jump tabs|
|Apple + w||close current tab|
If you like staying off the mouse and haven't heard of the incredibly useful, and unbelievably free, Quicksilver, you should check it out. It's an application launcher, mail checker, iTunes controller, Twitter sender, folder browser, search tool, etc. It's become one of the most useful apps I've ever used. Anyways, hope this was useful, cheers!
This just in: Exhaustive list of keyboard shortcuts, obscure and all!