>>3...I myself like "thank you"s because they are easy to give, show that it was worth the time to even bother, and give me a warm fuzzy feeling...because how often do you see someone bother to show courtesy on the net with "please" and "thank you"s?...of course two words may not seem equivalent to a picture or group of pictures...as I hear a picture is worth a thousand words...but in this way it makes it easier for others to repay me in exchange for helping them if they wish to do so...and who knows...if someday in the future I actually make a request of my own others who I have helped in the past may just want to try a little harder then normal to answer that request..."give a little get a little" as they say...or perhaps in your wording...
01: Get "thank you"s.
02: Build up incentive for others to help me.
03: Profit!!!
...if this will work or not I can not say...but the "thank you"s are really nice to get regardless...