These are services from people I know and recommend very highly:
Voice Teacher in New York City and Via Skype:
Atarah Hazzan is a Metropolitan Opera Star. She is the Co-developer of the BreathingRx for Singers System and one of the most innovative teachers in the world. She teaches every voice type singing any style of music. For voice lessons that help you progress at amazing speed and are also enjoyable. Her site: www.atarahhazzan.com
Vocal Jazz Improvisation Lessons in New York City and Via Skype:
Janet Lawson is a Grammy Nominated Improvisational Jazz Singer and Educator. Her site: www.janetlawsonscats.com
Performance Coach in New York City:
Marcy Jellison
offers private voice lessons, working in accordance with BreathingRx For Singers principles and developing singers of all styles of music. She also serves as a vocal production coach in preparation for and on location at studio recording sessions. In addition to vocal technique, Marcy Jellison coaches singing/acting and repertoire interpretation. Her site: http://www.marcyjellisonvoicelessons.com
Studio Engineer for Singers in New York City:
Sean Swinney is a specialist studio engineer for the singer. He has his own studio and very reasonable rates. He can be reached at 212-262-2249
See Steven Flam also on a service booking site called Thumbtack