Safari finally (in version 1.2) supports keyboard navigation to links and form buttons. I used to say that someone at Apple should have been fired for allowing Safari to be released with no possible way to access form buttons using the keyboard (even in full keyboard accessibility mode). This egregious error can at last be corrected by checking "Highlight links as you press the Tab key" in the Advanced preference pane.
I discovered that you can directly type the fi and fl ligatures with Option-Shift-5 and Option-Shift-6! No more hunting around in the Character Palette. Mnemonic: hit FIve to get FI.
You can also directly type left and right single quotes with Option-] and Option-Shift-], and left and right double quotes with Option-[ and Shift-Option-[. No more need to type out entities like "“" and friends.
This isn't a new discovery, but just to round out the list: there's never a need to type out "–" or "—" — just hit Option-hyphen or Option-Shift-hyphen.
It has always been possible to assign any shortcut keys to any application menu commands using the Keyboard Shortcuts pane in the System Preferences — but i've never had the patience to go in and edit that list of key combinations. Now Menu Master makes it easy enough that i might start doing it: you just hit a key combination while highlighting any menu item.
LaunchBar is a neat little tool that lets you navigate everything by typing a few letters. Hit Command-Space to pop up the bar, then type in a few consecutive letters or the initials of any application, bookmark, filename, or address book entry. Pretty speedy.
I only have two remaining beefs, i think:
No easy way to get to menus from the keyboard. The best you can do is to hit Fn-Ctrl-F2 to highlight the apple menu, then hit the right-arrow a bunch of times to get to the menu you want, and finally the down-arrow a bunch of times to get to the command. Why can't we use initials? Can't the Mac match the simplicity of Windows menus, e.g. Alt-F-S for File > Save? Lots of menu commands don't already have shortcuts, and even if they do, i don't have them all memorized.
It takes two hands to hit "Page Up", yet there's a whole useless key devoted to "Enter". How stupid is that? There are even two empty spaces on my iBook keyboard right above the left and right arrow keys, where most sane laptop keyboards have dedicated Page Up and Page Down keys. I want to remap Enter to behave like Fn so i can at least hit Page Up and Page Down with one hand. (I think it ought to be possible to do this by hacking the source code to uControl, but i haven't gotten around to that yet.)