I use mineral oil on cutting boards that will be actually be used. Doesn't go rancid like vegtable oils will. I have always wondered about using it is a preservative on a kayak frame. I was doing some research and ran across this on Wikpedia

Preservative

Since it does not absorb atmospheric moisture, mineral oil is useful as a protective coating or bath for water-sensitive materials. Alkali metals like lithium are often submerged in mineral oil for storage or transportation.
Mineral oil is also often used as a coating on metal tools and weapons, knives in particular, as a way to inhibit oxidation.

The Japanese swords Nihonto, for example, are traditionally coated in Choji oil which consists of 99% mineral oil and 1% oil of cloves. The use of oil of cloves is sometimes explained as a means of differentiating sword oil from cooking oil to prevent accidental ingestion, but may also be purely aesthetic.

Mineral oil can be used as a leather conditioner as well, though most shoe polishes use naphtha, lanolin, turpentine and Carnauba wax instead.

It can also be used as a wood preservative. A light coating of mineral oil, rubbed into well-sanded wood, provides an easy-to-apply and relatively durable finish, without the odor or drying time (or toxicity) of varnish or urethane.