Valleywag offers a way for Google Maps to bring out the evildoer in you:
1. go to http://maps.google.com
2. search for, say, "sex addicts"
3. choose a listing
4. hit the call button
5. when prompted for a number, enter the hated one’s digits
Link: Prank calls from Google Maps – Valleywag. (Thanks to Cara for spotting this on Gawker)