Haven't really be on this forum much but I came across this dock on Amazon. It's much cheaper then the OEM one and it comes with a AC adaptor, USB cable, and supports 2nd battery. Anyone try this out? Might be worth a shot for the price. Only thing it doesn't mention is if it enables multimedia mode when seated in the cradle.
Amazon.com: Motorola Droid USB Sync & Charge Cradle (with AC Charger) (w/ 2nd battery support) (Free OrionGadgets Neckstrap): Cell Phones & Service