Yeah, I haven't felt comfortable with oils yet. THey're really easy to blend, but it's a mess I'd rather not get into right now. My work area is my basement, which I share with all sorts of junk and tools, etc, so I don't want to bring in any more un-needed equipment.
Burnt umber, EVERYONE mentions somewhere. Give it a shot. I use it a lot. I even water it down and use it to create a splashed-mud effect.