What this coin looks like (obverse, reverse, mint mark location, special features, etc.): One major variety is the 1888-O Morgan Silver Dollar featuring a Doubled Die Obverse (DDO) error. This variety is sometimes known as the "Hot Lips" Morgan Dollar or VAM-4 variety. The doubled die error features a doubling of the Lady Liberty portrait - particularly the lips/nose/chin area. The lips are very clearly doubled (hence the Hot Lips name) and part of the nose and chin are doubled. At the back of the liberty crown - there are a few leaves and features doubled as well. These features are depicted by the arrows in the enlargeable example image above.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD