George Zimmerman Lawyer -- I Hope His Paintings Make MILLION$

George Zimmerman could have a gold mine on his hands -- selling artwork to climb out of massive debt -- and no one's happier than the lawyer who defended him at his murder trial -- who's still waiting to be paid ... TMZ has learned.

Zimmerman is on the hook to attorney Mark O'Mara for a reported $1 million. Zimmerman could make a serious dent in that debt if he sells his first original painting on eBay ... because the highest bid is now well over $100K.

O'Mara wouldn't comment on Zimmerman's finances. But he did tell us, "If selling paintings helps him rebuild his life, I'm not going to stand in the way of that."

But we're guessing if there's a big fat check in O'Mara's mailbox ... he'll gladly cash it.