I don't know of any already available set of Greek flashcards with pictures, although Randall Buth's print materials in his intro course of Koine Greek includes pictures (and accompanying audio CD). Here's a link to a demo: http://www.biblicallanguagecenter.com/sample-greek-lesson/
I am working on some materials for myself which I'll be glad to share, using PowerPoints instead of flashcards. Right now I'm working on a set to teach the numbers 1-10. I plan to do a set of four, one for each gender (masculine, feminine, neuter), and one summarizing the case forms and giving examples of usage from the Greek NT. I'm almost finished with the first one, on feminine forms. It uses pictures, animation, and sound files. I use this format for each number: number + color adjective + common, concrete noun. Here's what I have in mind for each gender:
Feminine: red ball
Masculine: brown bread
Neuter: white book (scroll)
That way, you learn the vocab item in a meaningful context, not just as an isolated word.
Thus: μια ερυθρα σφαιρα, δυο ερυθραι σφαιραι, κτλ. (one red ball, two red balls, etc.)
I should have the first set finished in a week or two. Let me know if you would like a copy and provide an email, if so, and I'll be glad to share them.