Polypropylene (PP) Hair available on the Internet can be a great substitute for fur or other forms of hair. The advantage is that it has a specific gravity of less than 1, .91 to be exact which means it floats. It usually is called super jumbo braid and a large quantity can be purchased for under $2.00 plus shipping. It comes it a variety of colors and blends. The hair should be identified as Polypropylene or PP if not contact the supplier before purchasing. One supplier to avoid is ragdollhair, who may also be listed as ragdolly.net, their service is extremely poor.
Natural Latex Rubber Tubing is another material that can be used to tie "Unsinkable Dry Flies." The material comes in sizes with an inside diameter of 1/16" to 1" with the most useful sizes being 1/16", 1/32", 1/8", and 3/32." The best wall thickness is 1/16" to 1/32." The tubing has specific gravity of less than one and will float even without an air bubble trapped inside. Colored tubing is available but is expensive compared to the natural color shown here. The tubing can be colored with permanent marking pens or inside with the use of alcohol based ink. 
It also works extremely well to tie nymphs. An example is shown to the left -- simply wrap the hook shank with lead and slide the tubing over the wrapped shank -- Then add skin, legs, antenna, etc.
