I note that the following noir films, which aren't available on DVD, are showing on TCM this month (April, 2009):
Danger Signal, April 13, 7:30 a.m.
So Long at the Fair, April 17, 10 p.m.
Naked Street, April 21, 9 a.m.
The High Wall, April 23, 8 a.m.
Rage in Heaven, April 23, 10 a.m.
The only one that I've managed to already see is "So Long at the Fair," about a young woman whose brother inexplicably disappears without a trace at the Paris Exposition--and I recommend it.