As you, all Mac users, have already noticed, installing the Android SDK tools on OS X is a little tricky. In this thread I've described an easy method of adding that support in OS X.
Prerequisites: open System Preferences, go to Security & Privacy and make sure the field Allow apps downloaded from is set to Anywhere. If not, the click on the lock in the bottom left corner, enter your user account password or just press Ok if you don't have such and change the radio button to Anywhere.
Ok, let's start:
1. Download the attached file and extract it somewhere on your Mac.
2. Double-click on the package file, you'll see something like this:
Click on Continue.
3. In the next window just select Install:
Sometimes you may be asked about the install location (usually when you have more than one volume), in such case just select the volume where OS X is installed.
4. In the next window enter your account password or just press Install software, if you don't have such:
5. The installation will begin and when it's ready, you'll see the confirmation window:
You have now installed the adb and fastboot binaries on your Mac! To check if everything is fine, go toLaunchpad, then Other, open Terminal and issue any of the two commands (adb or fastboot). If you see something like this (for fastboot):
then you're good to go.