My sub is at the front of the room, smack in the middle between the right speaker and the wall, and about 9 or 10 inches from the front wall, facing forward. The bass sounds pretty good from that position, but I don't have a lot of options regarding sub placement due to furniture. It's a wee bit crowded around here! I can move it left and right about a foot or so, and it seems best right in the middle, so that's where I've left it. It seems to be the perfect placement bearing my restrictions in mind.
cheers,
supervij