Android and Windows: Transferring files to an Android device is a pain. Air Drive lets you wirelessly mount your Android file system as a drive letter in Windows Explorer.
Mac/Android: Plug an Android into a Windows or Linux machine, turn on disk mode, and your phone is basically a drive. Plug into a Mac and you get a warning. Google’s own utility fixes that.
Mac OS X is, fortunately, blessed with a variety of really nice file transfer apps that support many services and protocols. Nonetheless, Transmit still manages to be the pick of the lot.