So GREAT! TinEye is a reverse image search engine

TinEye is a reverse image search engine. It finds out where an image came from, how it is being used, if modified versions of the image exist, or if there is a higher resolution version. TinEye is the first image search engine on the web to use image identification technology rather than keywords, metadata or watermarks. It is free to use for non-commercial searching.

AND
With the TinEye browser plugin is the fastest way to search for web images right from Firefox, Chrome, IE, Safari, or Opera. With the plugin installed, you just right click on the image!! any image wherever you encounter it.

Find the post of any image on the web, (including yours) This will show theft, misuse, posts without credit... OR if you DO want to credit or find the appropriate person to contact for purchase or permissions..

TRY it!
www.tineye.com/