You can use stethoscopes (or possibly probing) on eggs to identify them.

Dwarves don’t tunnel within Minetown limits (they can dig up the outer areas of the level just fine).

Hallucinatory message for squeaky boards: “You hear a chicken squawk a B note loudly.”

Dragon scale mail changes the color your character renders as depending on the color of the mail.

A “blank ring”, which has no powers. A gemstone can be inserted into it, which will turn it into that type of gemstone ring, whatever it happens to be. Possibly can be obtained by canceling other rings.

Cancelled trolls won’t rise from the dead.

A number of ways for weapon enchantment to be learned without formal identification.

• Rubbing it on a blessed touchstone
• Making a number of successful hits with it
• SLASH’EM’s weapon practice technique
• Making a number of attempted hits with it (they don’t have to hit)