maintain internet while sleeping?

If you add a display adapter to the DVI port on the MBP, it'll stay awake when the lid is closed, but, if the Mac is asleep, it's asleep - no connections, no apps running, etc.

 

Are you saying they always have to go to sleep when the lid is closed? Like, by default? That's.. bizarre. If so, shouldn't that behavior be easily changed in System Preferences somewhere?

 

It's not that bizarre. It's a fail-safe measure to ensure the thing won't overheat or get jolted whilst still accessing the hard drive. As far as I know, you don't necessarily need a cable in your DVI port. You can connect a mouse or keyboard to wake the thing up too, unless the newer machines are different.