I think there is a market there if someone pulls off a comments bits style service properly.

I used to make a living off of menus in that sort of way, although I moved away from that particular market as it seemed that most of the people wanting customised menus were wanting super bizarre highly user unfriendly menus which made it somewhat unmotivating to work on. Plus the advent of the WordPress menu system somewhat killed off the purpose of my menu plugin(s). The concept did seem to work though.

I had a vague plan of doing something similar with sliders, but shied away from that in the end. But I do think the idea is a sound one if someone were willing to put a lot of time into preparing some kick butt pre-made templates and systems for it.