The Monstrous Misadventures of Rusty & Co.

[RustMonster]

So, yeah, I've got a bad feeling about this.

It's a fair concern, Gamall. I've done a lot of research on it, and I can't find any indication that rust monsters are a copyright of, a trademark of, or a product identity of Wizards of the Coast, or TSR before that, or even of Paizo publishing. In fact, on the d20 site you linked to, rust monsters are NOT on the list of monsters considered product identity of WotC. (Second question on the FAQ.)

I'm confident I'm good to go on the legal side, now I just need to rustle up more votes.