What type (brand) of hygrometer do you use?
Kestrel 4200
Measures:
Humidity Ratio
Relative Humidity
Current Air Velocity
Max Air Velocity
Air Flow
Temperature
Barometric Pressure
Dewpoint
Wet Bulb Temp
Altitude
Heat Stress Index
Density Altitude
Wind Chill
I like multi-use tools and this works great for me doing mold inspections, HVAC inspections, and checking dryer vents. It’s a little more pricey than those little stick type hygrometers out there, but I don’t have to carry around a bunch of other tools that would add up to be a lot more.
Radio Shack - $30 and it is as accurate as my other UEI unit that cost $100. The batteries have to be 5 years old in it and it still going. You can hit reset and it record highest and lowest as well. Sometimes simple is just as good or better.
Wow- prices from $350 to $30! I think I need to do more research on this one. Thanks for your replies. Best wishes for '09! 
Extech 45160
Hygro-Thermo-Anemometer
Uei - $95
Dan-
Is that the DTH 31?
Very satisfied with those ones:
http://www.industrial-needs.com/measuring-instruments/humidity-meters.htm