I have always been curious as to how the SE's treat this.  Yes, it is probably not a good idea if you are hosted on the same server as the rest of your client's websites, but looking at the current proposed changes as to what may possibly be a penalty, I think that it wouldn't matter much where they are hosted.

I am really interested if anyone has any suggestions or thoughts on a way to give a creative credit to the organization that created the design or creative work i.e) "website design by company " using a micro format or HTML tag.

If the word coming down the pipe is a concentration on natural optimization, then calling a brown dog, a brown dog so to speak by using the proper citation would never be spammy. So linking to your website with "website design by company" shouldn't be penalized, nor should it require a no-follow if it is citing the creative origin, right? Am I making sense, it would be no different than an Author citation.

Reading on this topic today made me think about this, so what would be the most appropriate, a micro-format or some other tag? IDK, but if I come to a conclusion, you will be the first to know.