I'd say it's okay as long as it's just every once in awhile, but you should space them out a bit. Maybe 1 non-Joe shot for every six or so normal ones.
Some people post a lot of off topic stuff but it gets pretty annoying, especially since a lot of members come to this site to see GI Joe stuff and not the constant onslaught of Marvel, Transformers and what have you.
Of course, you could do whatever you want on a site like Flickr, so that's something to think about too.
