When making up the list of authors who have written for both NY publishers and e-pubs, I can't believe I forgot Jenna Petersen, aka Jess Michaels, who runs the Passionate Pen, an extraordinarily helpful site for writers. She writes for Red Sage Publishing and Venus Press, and her first Avon book will be released later this year.
There are also authors who write for epubs and somewhat smaller print publishers, including Marjorie Jones and Shelley Munro (who both write for Medallion Press as well as e-pubs) and Michelle Pillow (who writes for NCP and Virgin Cheek).
And when I posted about this on a list, someone suggested I add Sherrilyn Kenyon to the list as well. Sure enough, I checked her site and found this information: "The rarest of (Kenyon's) books is the e-novel Born of Fire (one of the first e-books ever published in the mid 1990's and a launch book for Dreams-Unlimited)." Wow... I had no clue she'd ever written an ebook!