I've been seeing some threads started by people who for one reason or another, can't seem mount their droids or don't know exactly how to.
So I thought people that have found resolutions in different forms could post here so someone could come here and see the different possible fixes all in one spot and hopefully get their issue resolved. Just throw out the checks-and-balances that has worked for you.

To start, I'll throw out an easy one, when my computer recognizes the phone plugging in to the USB but there's no drive showing up, turning on the USB Debugging solved the issue.

home screen>menu>settings>Applications>Development and check USB Debugging.