I belong to too many. All are in the burn mode or have completed burning. I kept miles like a bank account until 2001 then burned them whenever possible.
American - active, burn mode, now down to 65,000
United - inactive, burn mode completed, orphan miles
Delta - active, burn mode, now at 80,000
Northwest - slow burn, now at 150,000 (highest balance 441,000, >700,000 earned)
Continental - inactive, burn mode, now at 25,000+
US Airways - active, but all burned to 10,000 mi. now
Southwest - active, they burn it for you every 16th credit
AirTran - inactive
Lufthansa - inactive, burn mode completed
Jet Blue - orphan miles
Midwest - orphan miles transferred to CO via Amtrak
Frontier - orphan miles, may transfer Amex points here, maybe not.
(Hilton) - many points, now on burn mode
(Holiday Inn) - not too many points
(Choice/Sleep Inn/Comfort Inn/etc) - enough points for redemption, did redeem a few times before
(Red Roof Inn) - inactive, did redeem in 2005
(Econolodge) - burning