[lone-commenter]

To "disable" the Dock — not really: it will pop up sometimes, e.g. when some icon bounces, but anyway — you can

    defaults write com.apple.Dock autohide -bool true
    defaults write com.apple.Dock autohide-delay -float 100
    killall Dock

Here 100 is how many seconds you will have to keep the cursor on the edge of the screen before the Dock appears. You could set it to 3 or 5 should you need the Dock sometimes but don't want to trigger it by accident.

[Edit: Autohide can be toggled on/off also with ⌥+⌘+D. You can use the combination to show/hide the Dock, paired with a high autohide delay.]

[gcanyon]

Thanks! Yep, I used to set the delay to a long time, but I gave it up because my post above is a slight lie -- when something pops up in the dock to notify me, I go to the dock to see what the heck it was. That one use case caused me to give up setting a long delay because of how f'ing annoying it is for something to pop up, and then need (I think I set it to) 5 seconds to figure out what it was.