Everyone can use some muscle! Why sit around waiting for your client to pay, just so you can email them files. When they pay... Pancake will deliver the files for you! It's like a nicer, friendlier file hostage situation.
So this friday night - rather than waiting for payment - send your client their invoice and then go to that Justin Bieber concert you were so excited about... or drink beer. Your choice. Whatever you do, you don't have to wait on your client.