Over at The Luminous Landscape is an interesting discussion about the curves that are used by Adobe Camera Raw and Lightroom.
Having gone to the trouble of learning how curves work in photoshop and Capture 1 I have always foud the system used in Lightroom and Camera Raw rather confusing. I look forward to working out how its all supposed to be used.
Creating Web Galleries in Lightroom
Controlled Vocabulary and Lightroom