The Craft & Vision series of eBooks from David duChemin and friends is one of the most cost effective resources I've found to help develop a artist's eye in your digital photography. The basic goal of the series is to help improve one's photography without the need for any new or additional gear.
The latest installment, Below the Horizon – Understanding Light at the Edges of Day, by Dave Delnea, is a great read for those who love the light from the "magic hours" of dawn and dusk. Getting the light right makes such a huge difference in the quality of photos, and Dave provides several examples of how different times of the day invoke different feelings and reactions.
I highly recommend Below the Horizon, as well as all in the eBook series. I have them all!
Now, my biggest challenge is to figure out how to get out and shoot at these times while juggling the responsibilities of a husband and dad. So many things I want to do, so little time.