I'm not big on running in the rain -- which is why I begrudgingly head for the treadmill when the raindrops are falling on my head. But...there's no reason you can't run in the rain. Some people even enjoy it.
A running friend asked me the other day for tips for rainy runs because she was planning to meet some friends for a run on a rainy day.
The best I could come up with was...wear a windbreaker and a hat (I can't stand water dripping in my eyes).
I have since found better info online at about.com. Read it here. I figured I'd share this now since it looks as though we are all in for a few days of rainy runs (unless you are made of sugar, like me, and retreat to the treadmill).

