This forum hasn't been touched in a few years, but I know first hand that sharking is alive and well in the Twin Cities metro. I've met a few of the local sign sharks, and I've started a blog for my own efforts.
You can search for a thread on "CAUSS stickers" that describes how to easily make them.
We found that stickers: - Drew public attention to the sign spam problem. - Informed people that they, too, could remove illegal signs. - Recruited lots more sharks. - Let Code Enforcement know that people were dissatisfied with the limited budgets and priorities of CE. - Got the attention of the media. We got coverage in major media outlets and on prime time TV.