You might be a language geek if you ever thought...
Wouldn't it be great if there was a program that you could feed an identifier, tell it a language, and it would tell you if that identifier was valid for the given language? Or tell you useless stuff like all the languages the identifier is valid in? Wouldn't it be great if this program knew all about identifiers in any programming language you could think of?
You might also just be too lazy to memorize the rules or try running a program with it, and too particular to go with something safe, an identifier you know will work.
The inspiration for this idea: I want to know if hyphens are OK in CSS identifiers. It turns out they are (the W3.org syntax reference says so).
This sort of question pops up a lot in my experience, and I suppose the identifier question is not that critical. But the idea of a one-stop language reference with some level of interactivity is appealing. So, I think there's room for a C3PO "protocol droid" program that just knows stuff about all the languages out there. Rules for identifiers would be a decent place to start, followed by rules and information for simple stuff like constants and literals.
As is often the case with my ideas, they've already been done, marketed, and obsoleted by something better, so if you know of an implementation of this idea, leave a comment.