On talking dirty:
Gabriel, Bonnie. The Fine Art of Erotic Talk: How to Entice, Excite and Enchant Your Lover With Words, Bantam Books
Queen, Carol. Exhibitionism for the Shy: Show off, Dress up and Talk Hot, Down There Press
On being a sex worker:
Meretrix, Magdalene. Turning Pro: A Guide to Sex Work for the Ambitious and the Intrigued, Greenery Press
Phone sex fiction:
Baker, Nicholson. Vox, Random House
Lloyd, Joan Elizabeth. Velvet Whispers, Carroll & Graf Publishers, Inc.
Websites with links to professional phone sex services:
http://www.phonesexcentral.com
http://www.800phonesexsearch.com
Newsgroups:
For phone sex ads:
alt.personals.phone
alt.sex.phone
alt.sex.phone.ads
alt.sex.telephone
alt.sex.telephone.ads
alt.sex.masturbation
For general sexuality discussion:
soc.sexuality.general