You can share files between your Android device and a Mac by using a USB cable and running Android File Transfer on your Mac. If both devices are connected to the same Wi-Fi network, however, there's an easier way: Droid NAS. Droid NAS is an Android app that makes your device appear in Finder as a Bonjour computer. There's no need to open a Web browser or run a separate program on your Mac.
Launch Droid NAS on your Android device, then select which profile you want to use. You can choose among the three profiles that are preconfigured: Home, Office, and Cafe. Once you've selected the profile, tap on the "Start Server" button.
Your Android device should now show up in Finder on your Mac and you can begin transferring files back and forth..
The Droid NAS settings allow you to change the name of the server, choose a new Finder icon, restrict access by users, and choose which profiles to load when connected to different Wi-Fi networks.
While Droid NAS certainly isn't the only way to transfer files from your Android device to a Mac, it's drop-dead simple to use, and being able to manage your files within Finder is very convenient.