Another one to look at is Noodler's El Lawrence. It's a weird color (descriptions of it as looking like used motor oil are pretty accurate). But it's dark enough to pass for black without actually being black (more of a dark grayish brown), and it's pretty permanent and water resistant. It's one of the inks I wouldn't hesitate using for signing checks (Noodler's 54th Massachusetts and Noodler's Kung te Cheng being others, but El Lawrence is better behaved than KTC (which is one of my favorite inks but it does get cloggy).
Ruth Morrisson aka inkstainedruth