There’s a global project dedicated to this same idea!
http://www.you-are-beautiful.com/NEWS.htm
People put up stickers that simply say “You Are Beautiful” for passersby to see and notice and smile. Or people become inventive and display the message in other ways. Someone in NYC stood outside a subway station and handed out flyers to people exiting the station that read “You Are Beautiful.” I guarantee you all those people walked into work that morning with a smile.
Here’s one I did in college. When I came back to class after writing it, I saw that someone had seen it and responded!
http://img.photobucket.com/albums/v294/IIOII/youarebeautiful.jpg
Here’s a link to a livejournal community dedicated to the project:
http://community.livejournal.com/arebeautiful/
Do it!! They’ll send you the stickers for free. Just send them an envelope.

