Ruby and Python are now too good at doing webby stuff in that there are not enough Ruby devs to meet the demand of companies without skyrocketing salaries. It is easy to hire good Ruby devs, provided you have $400k to spend per year, but that isn't your real question.
Your real question is what languages will people really, really want to work for my company to use because nobody else is using them. I can only think of a couple: Common Lisp, Closure, Scheme, Smalltalk. There are others that are happy-fun languages but not necessarily I love you languages that few startups are using: Scala, server side CoffeeScript, Io, F#.
But the problem you run into there is that many of these languages don't have as many webby aspects to them which is why fewer startups use them in the first place.
I'd probably recommend Scheme because it has the best book of all time: http://www.amazon.com/How-Design-Programs-Introduction-Progr... That book can teach anyone how to code Scheme. Although all the languages I listed are awesome.