If they're fairly standard connectors of a usb-compatible variety, what I do is buy an adapter. Like this is a Lightning (apple) adapter: http://www.amazon.com/dp/B0183SA0R8/

It also comes with an attachment to the hook it to the cable.

I don't have a charger for 8 devices, but this is what I use with 1 micro usb cable and charger at home and when travelling to handle the annoyance of several slightly different charger ports.