I love when someone comes up with a seemingly simple invention to help solve a universal problem. Case in point: the Rotator Swivel Socket ($8), which is perfect for plugging in oversize or awkwardly-shaped plugs. Attach it into any outlet before plugging in an oddly-shaped adapter, that way the rest of the outlets on the wall (or on your power strip) won't be blocked. You can lock the swivel mechanism into position, too, so if you find a space-saving angle that works with you, just lock it into place.
While I have a few gadgets this will be useful for, it'll probably turn out to be most useful in the bathroom, where my hairdryer's plug always seems to co-opt outlet space.