We all know that there are around a billion image stock sites out there (Okay maybe not quite that many). However, only a handful of those sites offer 'or claim to offer' 100% free PNG images and fully layered freePSDs. That's never the case there are always hidden charges.
Snipstock, the new image stock site that has got 'designers' and 'muggles' talking, do indeed offer 1000's of free small, medium and large PNG images to download with just a click of a button. PSDs on the other hand are also free if you sign up. There is nothing to worry about though, they don't ask for bank details or how old your cat is.
Oh forgot to mention, the images are all royalty free so you can do with them as you please (in a none crazed stalker way).