Who makes a good 9mm barrell either 11.5 inch or shorter? I also heard some one makes a .45 acp set up for the AR platform. Does anyone have more information on this?
ADCO has a 7" and a 5" in 9mm. They will cut one any size you want and any thread pattern as well…
Not sure about the .45ACP?
Noveske has some 8.5" and 5" barrels right now:
http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?cat=153
RRA, CMMG, ADCO cut downs, TROS, Colt (on the secondary market)
There is a gentleman here in FL named Ron Williams who does a real nice DI 45ACP upper. He is also working on a DI 9mm upper if that is any interest.
BCM. It is basically a Colt. 
C4
Green Mountain Barrels
BCM has 10.5" bbls from time to time.
Lothar Walther makes a 5" with tri-lug.