Gray Jedi do not exist. It is a mistaken view stemming from Qui-Gon's disagreement on viewpoints with the Council. He is a Renegade who breaks the rules, but he is unmistakeably aligned with the Jedi, the Republic, and the Light Side.
Jolee Bindo can choose to reject a side of the Force all he likes, but he is still a Jedi and still fights for the good guys.
Kreia is a Sith Lord. No.
Kyle Katarn has issues dipping into the Dark Side for power, but the canon ending for Jedi Knight is that he chose the Light Side. For Jedi Outcast, Kyle Katarn is falling to the Dark Side before pulling himself back to the Light but retains his ability to use Lightning, which has been retconned by the Jedi vs. Sith Guide as being accessible to Jedi without falling (though I think that is slightly silly, but there you go).
Kyp Durron fell to Kun's manipulations and was redeemed.
Nejaa Halcyon? Jedi Master, disappeared upon death, indicating Light Side status. I don't see anything indicating Gray.
Qui-Gon Jinn was not Gray. He disagreed with the views of the Council. That is all. See what I said above.
Quinlan Vos also has issues, like Kyle, in dabbling with the Dark Side. But he is redeemed every time (that damn revolving door policy...)
The Exile and Revan do not qualify; canonically, the Light Side ending is followed, making them good guys and Light Siders.
Cade Skywalker is falling to the Dark Side, one outraged burst at a time. Only a matter of time before he will need to be redeemed...
Aurra Sing is a Dark Jedi, no mistaking that. She's evil, kills Jedi (sometimes not even because of a bounty), and relies on her hatred for power.
Vergere, due to her sowing the seeds of corruption of Krayt and Caedus, and temporarily studying under Palpatine, I would qualify as a Dark Sider. Or redeemed, I guess. Hard to tell with her, but there is no in between.