I'm doing a google search for "free Harlequin ebooks" and so far I haven't seen any more current offers, but I DID notice that the last couple years, either for the whole month of December or the week between Christmas and New Years, eHarlequin offers a free book each day. I wasn't into ebooks yet last Christmas, so I didn't pay attention, but I definitely will keep my eye out this Christmas.
In the process I also found this
really cool site that I had heard about but not really explored much. I will definitely go back and explore some more after I'm done with my search.