Paint Buddy

Paint Buddy is a paint roller with paint refinishing onboard storage. After painting a room, the user stores excess paint the project in a Rubbermaid Paint Buddy and labels of the CAP with the play and color information. Later, when a wall needs a minor touch-up, the user simply removes the clear cap, the valve opens and applies the paint in the region with the high-roller.

You can see here
http://www.paintbuddy.com/shurline/consumer/paintbuddy/index.jhtml; jsessionid = RTOTULGJWV0XOCQHUBSCF3QKA4QHQJCK

It sounds like a good concept. But I tried products like this, and they have not really impressed. It is more of a gadget and not a truly innovative tool. Martha Stewart offered a tip to the paint store in a glass or mayonnaise jar for touch. The container is free, you're recycling, and you can see the color of the paint across the window. I would just use a small brush to touch up.