Here's the regime I follow every 3rd ride, regardless of mileage (most of my rides are 30 - 80 miles):

1. Wipe the chain down with a dry terry cloth towel
2. Wipe the chain rings and cassette too
3. Put 1 drop of lube on each link
4. Wipe off the excess oil with the towel

This keeps my drive train silent and provides protection from wear and tear.

I've been using Pedro's Lube but will be trying Pro Link Gold next; I've heard it's one of the best for keeping dirt from sticking to the chain.