Krystall is great - and wholly underrated, in my opinion. That is a cool record - Neidlinger has some very interesting arranging ideas, to say the least.
In addition to those already mentioned, Giuseppi Logan was a wild bass clarinetist, as heard on Roswell Rudd's Everywhere and his own composition "Shebar" (More Giuseppi Logan, ESP). Frank Wright takes some heavy solos on bass clarinet in his duos with Muhammad Ali, Adieu Little Man.
Breuker was already mentioned, but I'l mention him again, as well as Theo Loevendie.