Indian Rosewood—used for more fingerboards than any other wood. Indian rosewood is not as wear resistant as ebony, but some people prefer rosewood's attractive grain to the uniformity of ebony. Rosewood is also cheaper than ebony, but the difference is really only significant on mass-produced guitars.
Rosewood's lightness is an advantage in bridges, but it's cross-grain weakness (compared to ebony) somewhat cancels out this benefit. More wood is needed in front of the saddle to keep it from breaking out.