1: The Making Of A Gigolo (1) - Tilly Johnson by Lubrican This series is the best I've seen at taking one lucky dude and finding reasons for him to hook up with many, MANY different women. I especially love this story as it's particularly kinky about knocking women up.
2: A Master's Ring by ElSol THE quintessential harem Master/Sub story. Now if only he'd ever finish it.