A friend pointed out the Flex Brake project on Kickstarter, pointed out to him by an Inline Club of Boston announcement. The product is an add-on braking system usable on most four- or five-wheel inline skates. It can be installed on one skate or both and is activated by pulling on a strap. If you're comfortable crouching over your skates, the minimal version's strap passes over your laces. For the less flexible skater, there's a leash you can clip near your waist and pull while standing.
Do I want this? I'm not sure. I'm usually skating on a good surface where the standard heel brake works well. Crouching to pull the brake strap might be awkward and the leash might look dorky. On the other hand, better brakes could give me more confidence in the occasional tricky situation.
Watch the videos, read the blurb, and make your own decision.