Since we've been discussing some typography tags:
As an example, I just tagged this question with EPS.
Generally, I think it would be good with more tag diversity. Format tags would be good, provided it is relevant to the question in the sense that discussing some effect in Photoshop does not require a .psd tag. It will of course have a photoshop-tag.
It would have to have some relevance to the question, not generally Photoshop = .psd.
On tag diversity in general, I think i would be good with a Meta post with some brainstorming.
I see tags as a fairly hierarchical structure, where you go from the most general to as specific as possible in five tags. Example; someone has trouble with layers and saving:
So, I am all for it.