A little while ago a company (Macally? thought so but didn't find it on their site) introduced a very very simple device-- as I remember, it was a small "nubbin" with a rotating dial that also allowed for push-button input.
Something like this would be ideal for a project I am working on (I need a USB push-button device to link to a QuickKeys macro that would do a screen capture and upload the image to a webcam server)