Recently, I've found myself using Google search queries as a kind of passive messaging system. For example, I make regular use of Dave's BBC radio stream pages, whereby the stream URLS are scraped from the BBC site and presented in a more useable format. By way of a Google search for Dave's site, I showed my appreciation thusly:
dave bbc streams -“thanks dave!"
If Dave checks his server logs he'll know that his service is appreciated.