Okay, I'm an ESL teacher, so a more recent usage with which I've become familiar deals with language. Some of my students use an acronym to remember the coordinating conjunctions of the English language. You know, those are the little words that help things stick together: For, And, Neither, But, Or, Yet, and So. I've been teaching English to speakers of other languages for decades, but I still avoid talking about grammar as much as possible. When painted into a corner, I will default to a descriptive attempt. I simply abhor prescriptive grammarians though. Regardless, I learned the second type of FANBOYS from students who've obviously studied a lot of it.
Most recently, I've run across the term due to a new interest in gaming consoles. The term has probably been around for about 25 years although its widespread use is more recent and has broadened. I have witnessed the rantings and ravings of this type of fanboy on the Internet. Basically, true to the Wikipedia entry, they have been written by adolescent boys who defend a particular console brand or game. Perhaps because of the content they're used to seeing, they are ready to defend their opinions to near death! For example, look at the comments appearing under the story on this blorge.com page. I suppose I should be encouraged by all the flaming just because it's good to see that kids can get so worked-up about anything. You'll have to forgive me though. I bought a PlayStation 3 not because I'm a fanboy, but due to the fact I enjoy watching Blu-ray movies.