NN/Group's Bruce Tognazzini compiled an excellent and exhaustive overview of principles for interaction design, that he considers fundamental for the design and implementation of user interfaces. Fundamental, so regardless of the application area, so I guess they apply to electronic consumer products as well.

The overview covers (alphabetized) subjects such as: autonomy, consistency, defaults, latency reduction, learnability, and track state. I especially like what he has to say on explorable interfaces:

Give users well-marked roads and landmarks, then let them shift into four-wheel drive
Mimic the safety, smoothness, and consistency of the natural landscape. Don’t trap users into a single path through a service, but do offer them a line of least resistance. This lets the new user and the user who just wants to get the job done in the quickest way possible and "no-brainer" way through, while still enabling those who want to explore and play what-if a means to wander farther afield.

More on interaction design principles and guidelines
> 101 things I learned in Interaction Design School
> Ergonomics crash course for interaction designers
> Pattern library for interaction design
> 30 usability issues to be aware of
> iPhone human interface guidelines (Apple)