Goodness180:
Here is one from Flow quil. ALl though i have never used it, i allways use test grey spray in a can.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXXA23&P=7
That's an excellent recommendation. I've used Floquil's Black Figure Primer alot and it's one of my favorites. However, Jackball asked for a black 'brush' primer and I'dont believe I've heard of one other than Vallejo's acylic one. Floquil bottled primer is available in grey and can be brushed or airbrushed.