Mills & Boon celebrates its 100 birthday this year, and there is a book out to celebrate it: The Art of Romance: Mills & Boon and Harlequin Cover Designs by Joanna Bowring and Margaret O'Brien. Click on the link in the post title to see some of the covers.
The first one is especially interesting - definitely a child of its time. I can't tell if he's supposed to be on the verge of attacking her or if he's supposed to have just found her, but I would like to find out.
There is also a contest in which you can win a copy of the book if you come up with a good title for one of the covers.