When it comes to the program of encouraging active users, everyone somehow immediately thinks about the money that needs to be paid. Here is a simple idea, which, of course, does not cancel or replace money, but will inspire “creatives” quite well.
User created 100th topic? Did a dozen useful, "plus" comments? “Flown” a month of clean time? Congratulate him on this! A small “Easter egg” is a great encouragement for the author, a charge of viral marketing for the site and, besides, not a bad fun for the developers themselves. In short, it is a pleasure!
How to do it - you decide. Lightbox with a greeting card, a separate colorful page in the interval between posting and viewing the result, a message to the internal or e-mail, the title of the topic, sparkling with salute splashes - only the first thing that comes to mind. Small detail: tell the user what you specifically congratulate him on, hint that this is not the last time and that the next congratulation on the same occasion will happen under such and such conditions. Be diverse and creative, everything is possible here, do not repeat - let people brag to each other how they were congratulated.
Happy web vebdanol