I love Tess Mallory's books. She can always get me to sit up all night because I just can't put it down. I haven't read Highland Rogue yet because I couldn't find it at the bookstore the other day. I'm heading over to Borders this week and should have it finished by the weekend.
Edit: Tess also has a new book coming out March 3rd. You can pre-order here or pick it up at your local bookstore next month.