Is there a way to make it so that launching an app from the dock requires a double click instead of a single click? I find myself accidentally launching apps and then needing to force-quit them.
I'm hoping for some OS hack or third-party app. Yes, I already have the dock hidden.
You can move the dock's location and size by going to System Preferences > Dock. Rather than keeping the dock at the bottom, where the mouse needs to be often, move it to either the right or left sides of the screen.
I auto-hide the dock on the left side of the screen (I'm on a 13" MacBook Air, so my vertical space is limited too). You could also use @VxJasonxV's suggestion of removing the apps from the dock. Most of the programs I launch are via spotlight (the ⌘+Space shortcut is very useful). And the last trick I use is BetterTouchTool. I bound five-finger-click to ⌘+Q, which makes it very easy to quit applications, but not so easy that it accidentally quits applications I didn't mean to quit.
Don't hide the Dock. You'll be less surprised when it pops out at you and eats your click.
If applications must be "force quit" when you accidentally open them, get them out of your Dock! Use a launcher like Alfred, LaunchBar, Quicksilver, or Google Quick Search Box. Or even Spotlight!
I rarely, if ever, use the mouse to open applications, much less use the dock.