The whole 30 For 30 series is actually a great look into some of the bigger moments in sports.
In terms of basketball related episodes you have:
Without Bias - Takes a look at the death of Len Bias, who died just 2 days after being drafted #2 overall by the Boston Celtics in 1986.
Winning Time: Reggie Miller vs the New York Knicks - Looks at Reggie Miller's battle with the Knicks in the 90's (1995 I think), and his interaction with fans, opposing players as well as Knicks fan Spike Lee.
Guru of Go - Focuses on the coaching tenure of Paul Westhead at Loyola Marymount University between 1985-1990. Interesting look at the up-tempo "Run-and-Gun" offense implemented by Westhead.
No Crossover: The Trial of Allen Iverson - Provides a look at the 1993 trial of then High School athlete Allen Iverson, convicted for his role in a racially charged melee and its impact on both the community and Iverson himself.
Jordan Rides The Bus - Takes a look at the breif Minor League Baseball career of Michael Jordan. An interesting episode which shows the types of things which Jordan was dealing with away from the game of basketball, as well as how close he came to playing Major League Baseball.
Once Brothers - The story of Dražen Petrovi? (Croatian) and Vlade Divac (Serbian), teammates on the Yugoslavian national team, and the war in their homeland affected and destroyed their friendship.
I downloaded the whole series as they came out, and after watching all of them I would definitely recommend any of the basketball documentaries for all fans.