Black & Decker's RapidRoller's frame pivots to three positions so that you can use it for different angles and jobs. It also sucks paint right out of the can through special lids and stores it in its body. The paint can then be applied to the roller with a squeeze of the handle. And to guard against your brilliant friends leaning their rollers unsteadily against a piece of furniture, it even comes equipped with a kickstand.
I recently helped a friend move into a new apartment, and he scheduled a whole day for us to come over and help him paint. This sounded like a great idea until we realised no one knew anything about painting. It took us forever. Maybe we could have used something like this. [Amazon via Uncrate]