Backronym

In doing a bit of research for Holy Crap! Facts about whether or not the word "tip" was actually an acronym for "to insure promptness" (it is not), I ran across the word backronym. The word is defined on Wikipedia as "a phrase that is constructed 'after the fact' from a previously existing word or abbreviation, the abbreviation being an initialism or an acronym." I thought that was pretty cool. Wikipedia also has a short list of backronyms.