Thanks for the replies.
Didn't Martina Hingis also work with David Taylor for a very short while when she decided to "take a break" from Melanie? This was in 2001 around the American claycourt season. Around the time Martina lost in the QF to Arantxa at Amelia Island.
Martina Hingis: Melanie Molitor --> David Taylor --> Melanie Molitor
Monica also worked with Gavin Hopper for a period but he was more of a trainer than a coach to her. Did Monica Seles ever work with Harold Solomon, or am I thinking of Jennifer Capriati? Speaking of Jen...
Jennifer Capriati: (Little help please?) Rick Macci --> Stefano Capriati --> Pavel Slozil --> Stefano Capriati --> Paul McNamee --> Stefano Capriati --> Harold Solomon --> Stefano Capriati
(She sure loves this Stefano Capriati guy, doesn't she?

)
Arantxa Sanchez-Vicario: (Little help with chronology please?) Juan Nunez --> Mike Estep --> Mervyn Rose --> Emilio Sanchez (and I'm quite sure there were others... The hussy!

)
That Marat! What a slut! So many coaches, so little time...
Jana Novotna: ??? --> ??? --> Hana Mandlikova
Does anyone want to have a crack at Martina Navratilova's coaching history? There must be quite a few illustrious names in there including BJK, Craig Kardon, Mike Estep and... (in chronological order, pelase)
Lleyton Hewitt: ??? --> Darren Cahill --> Jason Stoltenberg --> Roger Rasheed
Andre Agassi: Nick Bolletieri --> ??? --> Brad Gilbert --> Darren Cahill
Anna Kournikova: Nick Bolletieri --> Alla Kournikova (?) --> Who coaches Anna now anyway?
Amanda Coetzer: Dennis Van Der Meer --> Nigel Sears --> Gavin Hopper (as a coach or trainer?) --> Who coached her after them?
Jelena Dokic: Lesley Bowrey --> Tony Roche --> Wally Masur --> Damir Dokic --> Heinz Gundhardt --> ??? (I'm probably missing a few)
Pete Sampras: Tim Gullickson --> Paul Annacone --> (I can't remember who came after them)