Lots of vacuums have a convenient self-retracting cord -- such as the pictured Electrolux Eureka Brushroll Clean -- and I love this feature. Really, it probably only takes a minute to wind up the cord when you're done, but it's still one fewer aspect of vacuuming tedium that you have to deal with.
Certain Electrolux models have a unique feature called the Brushroll clean. Essentially a blade above the brushroll, you push a lever while the vacuum runs, and the blade lowers and scrapes away any stuck pet hair. It works surprisingly well and saves you from having to pick out those pet hairs yourself.
Speaking of pet hair, powered accessories make cleaning it off of your couch much easier. Certain vacuums, such as the Dyson v10, come with a specialized tool. This powered brushroll, for example, can grab hair more effectively than a wand.