Today the Smart Bitches have a review on a romance author, Alexis Harrington, who's Kindled her backlist. She has quite a list of Kindled books available (she's selling them for $4.25, but her sales ranking is pretty good, so yay for her-- wish I could get people to buy me at that price!). Other romance authors I've noticed lately with at least a few Kindled backlist books are Belle Andre and Karen Ranney.
ETA: Julie Ortolon mentions in the comments that she's Kindling her backlist and doing covers for others who are, too. She's blogging about the process here.