The other day I was at an Underground station where there were a number of charity collectors with buckets. I put a coin in a collector’s bucket and he gave me a bright yellow sticker in return. At first I was unsure about wanting it; it’s the kind of thing I’d have loved when I was 5 or 6, but it’s not important to me now. Also, I was slightly self-conscious about wearing it. Then as I continued on my journey in the station I realised wearing the sticker wasn’t for my benefit, it was for the charity’s benefit.
By showing the sticker—along with others who had given—I was sending a message along the lines of, “Here is someone else who’s made a donation—maybe you should, too.” Rather than the charity workers being isolated in the station they became part of a network linkng them with many of the commuters, and it legitimised further giving. “You, too, can become part of this network.”
I realised I do a similar thing when I’m introducing new working practices somewhere. I don’t just want people to do, say, test-driven development or planning in small increments. I also want them to talk about it, socialise it, and make the new practices become standard behaviour.
It is good to do good work. And it’s better to make that good work visible.
niksilver.com 
I agree with you. With this, it came to my mind when I was a student at the High School and a volunteer in the Red Cross and there were each year “The day of the small flag” (literal translation from Spanish. I’m not sure if this works on English) where we were in the street as some charity collectors and we gave people a white little sticker with a Red Cross and people used to continue their way proudly with them on their coats.