I started one for myself and will plow more into it later when I've exhausted other tax-advantaged options.
When I'm in retirement it is quite possible that I will take a class here and there, probably at a tech school. You can even do things like take an "art history travel course" with a college or university and it will pay for that.
Read further... I think there are some rich options with the 529.
Also, make sure you're taking the Lifetime Learning Credit, as appropriate. I took a work-related course this year. I'm using the LLC for the first portion (20%), then the 529 for the balance. You can't double dip, but the two benefits dovetail nicely. You can read much more about it on the IRS website.