This one is a great one: http://chiotsrun.com/2011/01/15/my-seed-organizing-stash/ There is a complete tutorial on organizing her seeds on this blog.
This one is from Martha Stewart:
To ensure that seeds wake up refreshed from their long winter naps, take the time to tuck them in properly. Moisture, heat, and fluctuating temperatures are a seed's worst enemy, so don't simply abandon your leftover packets to the elements by leaving them in a garden shed. By the next spring they will have lost much of their vigor -- the ability to germinate quickly and healthily -- and many may have died. Instead, place packets in an airtight container, such as a canning jar with a new lid. Then make a few moisture-absorbing sachets to store with them by wrapping 2 tablespoons of untreated cat litter (avoid colored or scented litters) or powdered milk in a double layer of tulle. Close the lid tightly, and put the jar in a cool, dark place.
This is a similiar method to Chiots Run above - a little differnt - great ideas!
Here are some templates for making smaller envelopes: