[Usability] combo box guidelines?

[Jacob Beauregard <jake13jake comcast net>]

Yea, I know I've probably whined about combo boxes enough, but honestly, 
does this image make sense to you?

This is just one occurrence in many that I've had. I can only see 3 out 
of 7 options. Less than half of the options being used is just not good 
practice. That's only 2 out of 7 odds (not good) that the service type I 
want is going to immediately visible and navigable.

While I believe it's a good idea to allow combo boxes to be open-ended, 
I just don't understand why visibility doesn't pay a larger role. The 
best argument I've heard is preserving motion memory. However, anything 
lacking in visibility is far from intuitive.