I love sidewalk signs! They are the purest from of marketing. Write a good one you can literally motivate customers to walk in you door. Where I live in Brooklyn I walk by many every day. Here are some quick marketing reviews of several I've passed recently.
The Josh Gordon Group blog
Angie Hicks Bowman, co-founder of the home service rating company that carries her name, is one of the smartest marketers I have ever interviewed. She started her company as "Columbus Neighbors," personally going door to door in Columbus, Ohio to sign up members and collect ratings on local contractors. After her first year of door knocking, her company had 1,000 members. Today, that number is over 1.5 million paid members.