I agree with all of the above. I like to have 2 GPS apps on my iPhone at a time: a less expensive but connected/easier one that needs a network connection (e.g. Motion-X Drive) and a more expensive but slightly harder to use one that will work when I'm in an area without phone/3G coverage (e.g. TomTom).
For videos I've taken to using VLC. It's incredibly easy to drag and drop all my videos, in all their different formats, on the iPhone/iPad so I can view them while traveling. Though I personally don't even like listening to music while I'm riding, I figure it's only a matter of time until someone starts watching movies in flight. Actually, now that I think of it, maybe there needs to be an iPad holder for the pilot's back so the pillion can watch while moving ;-).
And, of course, Greatest Road
holds the most prominent place.
Actually, I do use it on a regular basis as a consumer, and have found a whole bunch of unknown-to-me roads nearby.