I've been able to chip away most of the paint on my 1930's houses' plaster walls down to the plaster. There were two layers of paint and they came off very easily from the wall... almost like an eggshell off an egg. There was a border along the top of the wall, and the paint layers under the border are still adhered to the wall, and I'm having a much more difficult time removing this area of paint.

Are there any products which will - when applied - strip the paint off a plater wall without damaging the plaster? Everything I see is for woodwork. Has anyone tried any of these products on a plaster wall for faster and easier paint removal?

If somebody else posts that they have done it, listen to them. Most of the common paint strippers are organic based, toxic, flammable, but shouldn't hurt plaster. Plaster is lime and gypsum, and other minerals. Avoid anything acid which might include the citric strippers. The caustic based ones should be OK, but as usual, test in an inconspicuous area.

That old, the paint may be the old white lead and linseed oil. It may yield to the caustic more quick than the organic. I hope you have been careful, not breathing dust, cleaning it up good, and washing you hands. The hazards of lead in newer paint is greatly over hyped. Current law replaced a 0.5% standard with a 0.06% standard. There is no scientific evidence that up to 2% lead is harmful. Today's standard is mostly about keeping politicians in office and lawyers in Rolexes and BMWS, not protecting children. Removal contractors are in the gravy train too.

Disclosure, I was working as a chemist in the paint industry when the law was passed.

I'm typing several years after this question was asked, but for anyone else who encounters this issue:

The OP describes to a T a room in my 1940's house. Most of the paint came off the plaster like peeling an eggshell, but left a tightly adhered "border" around the ceiling line.

Well, after hacking a small area of that border away, I saw why it was there and decided to leave it. There was an ugly, very visible gap between the wall and the ceiling. Whatever that "border" is made of, it's there to fill in that gap and leave a clean line at the ceiling. I decided just to sand it and feather it into the wall surface, prime and repaint.