In the right column of this site, below the “Categories” and “Recent Readers” modules, is a “Want Good Karma?” module. It’s kind of subtle. I added it late last year after removing some CPM banner ads. Within it is this button:
My world-traveling buddy Jimmy was kind enough to buy me a coffee, provided I show a picture of the coffee he helped me purchase.
Well Jimmy, this one’s from you! Thanks man! I’m mentally beaming you good karma right now.