Launch an OS X app with a keyboard shortcut

Check out BetterTouchTools... its FREE!

The "Keyboard" tab in this application allows you to set any keyboard keys to "Open Application / File / Script" as well as many other useful things.

BetterTouchTools main purpose is to customize multi-touch devices... which is awesome! However, it works great for keyboard shortcuts as well. You may want to consider using multi-touch along with keyboard shortcuts. I find it to be very useful.

The picture below shows just a few of the things your keyboard shortcuts can do.

Assign not a Service keyboard shortcut, but a custom Application shortcut that works in All applications, and enter your service name as the name of the menu entry.

Third party applications that support assigning shortcuts to applications:

• Alfred
• Apptivate
• BetterTouchTool
• Butler
• iKey
• Keyboard Cowboy
• Keyboard Maestro
• Keymando
• Launch it!
• NuKit
• Quickeys
• Quicksilver
• Shortcuts
• Spark
• Twitch

I use Alfred, and I've used KeyRemap4MacBook to convert single keys to ⌃⌥⇧⌘ and ⌃⌥⌘.

You could also assign shortcuts to shell commands like open -a iTunes. AppleScripts like this are blocked until the application finishes opening, so they seem to take longer if they are run with FastScripts:

tell application "iTunes"
    reopen
    activate
end tell

You could also create Automator services:

There's a bug on 10.7 and 10.8 where the shortcuts for Automator services don't always work until you have hovered over the services menu from the menu bar. There's also a short delay before they are run, and they aren't available in applications that don't have a services menu.