There are already tags that may (or may not be) equivalents. How do we want to handle gm vs. dm and online vs. online-resources for example?
I think [dm] should be blacklisted (I dunno if we can do that in beta) as it's kind of DnD specific, while this site is RPG-oriented, not DnD oriented.
If someone tries to use [dm] it should give them a message informing them to use [gm] instead.
Sunno about the rest...