Agreed - I consider advertising and billboards to be a blight. I'm always pleased to see graffiti go up on some around here because it's so much more human - one-off pieces that took at least some skill and a bunch of risk to put up.

My SO and I once looked into the cost to rent some local billboards with the idea to just put up local artists work like some kind of outdoor gallery/museum (and deprive all the local politicos and anti-abortion groups the prominent space). It turned out to be cheaper than we expected but not enough to do on a lark - we'd need to set up some kind of organization and fundraise and weren't in a place to do that at the time so it went on the back burner.

Getting rid of them altogether would be better than paying into the existing system.