Lots of answers on this one. I have used Brass Black on steel and gotten a nice gray finish. Paint it one, let it go black and then wipe off with 0000 steel wool and soap. Repeat for an even finish. Coat with a good oil. Give a nice light gray that does not rust easily.
Naval jelly is a pink goo that you get at a hardware store. It is used to clean rust off of stuff but it leaves the metal a nice grey color afterwards. If you put it on non rusted steel it will greay it too. For me, it usually takes a few coats to get it to even out.
On my Hawken I did the nose cap and rib in gray (Brass Black, then rubbed back with 0000 steel wool). Did it 'cause I thought it looked cool. Oil once in a while, never any rust.
Nose Cap and Rib. You can see the color pretty good against the browned entry pipe.
Mike, you say "wipe off with 0000 steel wool and soap". Forgive me if I'm being stupid, but can you elaborate on the soap part? Do you mean wash off with soap and water, or are you literally rubbing a bar of soap on there?