LAST EDITED ON Aug-28-08 AT 03:08PM (MST)[p]Powdered chalk.
You can get it from sporting good stores in the weightlifting section, or wherever rock climbing supplies are found.
Ran out on a trip once and refilled with the dust on the side of the dirt atv trail. You know the kid of dust I'm talking about, 4 inches thick, and will choke you to death if you aint the lead rider. It worked well also.
I personally use the dust, leaves twigs or what ever is at my feet at that exact time I need to know. I tried one of those windchecker things once and it is just another gimic to carry in an already filling up pack.
Grass, dirt, twigs, yarn are fine for wind check, but its the undetectable gross air currents that are crutial and can only be detected by the finest lofty ariborne powder. I use a bottle or two a year, no gimick.
I have used an old nasal spray bottle filled with baking powder for years. It works great and I am still on my first can of baking powder. Just give it a squeeze and enough powder comes out. I like it because in a light breeze it stays suspended long enough to give a good read. Yea, I even wrapped camo tape around it.
Try cattails .... one cattail will last a life time too.
just grab a small pinch pinch and let her float.. you can see it float for a long time. Much better than poweders IMO ..a little goes a long way .I used to have some attached to my bow and with some tape.