Another new addition to the quiver in CS 5 was the ability to taper individual strokes. The Profile drop-down in the Stroke Pallet offers several options to manipulate a line width along a path. Width Profile 4 is very useful for achieving a tapered stream style in a hydrological network. It will taper any stroke from the set point size at one end, down to a finite point at the other. In addition, the Width Tool allows you to modify that taper at any point along the line, allowing you symbolize rivers in a much more natural way. Combine with stream classes from GIS attributes, and one can create a realistic branching network that tapers from a trickle at the headwaters and expands to a torrent at the outlet. Incorporate this trick into your next map, and set it apart from the rest. The video lays it all out.