John Thompson won an NBA title as a player with the Celtics in
1965-66 and then coached the NCAA champs Georgetown in 1984. Larry
Brown won an ABA title in 1969 as a player with the Oakland Oaks
and was the coach of the NCAA champs Kansas in 1988.
Ray Allen (UConn '99, Celtics '08) is the only one off the top
of my head.
Ray Allen wasn't on the 99 Uconn team that won the NCAA title.
Richard Hamilton was however and also won a title with the 2004