Air was Henry Threadgill's first group, formed in the early 1970s with
Fred Hopkins and Steve McCall (who died and was replaced by Pheeroan AkLaff).
They're more out than most stuff that gets discussed on this list, but I like
them a whole bunch. They put out 10 albums (I think) -- I particularly like
"Air Raid" and "Live Air", but they're all good. (BTW, I think they're worth
listening to if only for McCall and AkLaff, who are two absolutely phenomenal
drummers.)
Threadgill's done a bunch more with a few different ensembles (his sextet, the
Very Very Circus, Make a Move, and the Flute Force Four come to immediate
mind) as well as some non-ensemble work, and I pretty much dig all of it up to
his most recent stuff with Make a Move (who I saw this summer; I thought they
were kind of disjointed and dull) and the unfortunately conceived Flute Force
Four (which is just what it sounds like). As someone else (Robin Davies, I
think) has said, "Too Much Sugar For a Dime" is a great record (yeah, it's on
Axiom), and it's probably the rock-est of his recordings. Other than the
aforementioned Air records, which are (I think) his most free work, I'd also
recommend "Song Out of My Trees", and, um, some other records I can't remember
the names of.
(The idea of Laswell producing Air doesn't exactly make me comfortable...)