You know, although etching the bare frame with acid is an awful idea, you might be able to do something like it by having some sort of mask of the lettering made and having a sandblaster etch the lettering into the steel. Not sure just how that would work, but I know that the granite industry uses a similar process (I'm near Barre, Vermont, where they make a lot of gravestones) to etch lettering in stone. I wouldn't try it on a priceless bike, but it might be worth experimenting with. The effect might be subtle but maybe it would look kind of cool.
Anyone else ever heard of anything similar?
JV