Memorandums of understanding have been used to cover all sorts of agreements, and are sometimes made between governments instead of more formal treaties that would require parliamentary approval. (The United Nations' ill-fated "Oil for Food" program is one example.)
In the world of college basketball, the most notable memorandum of understanding is the one that governed Billy Gillispie's tenure as head coach of the Kentucky Wildcats. Gillispie and the Kentucky Athletic Association had a memorandum of understanding that outlined a seven-year deal to coach the Wildcats, but never signed a formal contract. In retrospect, that may have been a mistake; Gillispie was fired after the first two seasons of the deal, and later filed a lawsuit in an attempt to collect the money he believes he's due under the terms of the not-quite-a-contract.
