As a quick update to Trends in Technical Syntax: Hyphens and Underscores, I'm just posting to say that I'm now pretty much using hyphens in all my CSS classes and id tags.
And for URLs - always underscores for real files. For url "tokens" (references to resources, but not real files), I'll probably continue to use hyphens, though with the help of rewrite tools, I'm starting to use forward slashes, too.
I'm still not comfortable with CamelCase, though. It's just OK for two words, but beyond that, I have a bit of an issue. I use Javascript, jQuery,, Perl, and Ruby a lot these days, and they definitely use capital letters in mid-string. Seems like JavaScript functions start with a lowercase letter, and only uppercase the second word, while Ruby classes start and split words with capital letters.
Examples? BigDecimal (class) in Ruby and appendTo (function) in Ruby. And Perl seems to be a little different... subroutines seem to be all lowercase... no tower of babel here!!