"email" vs "e-mail"?
"web site" vs "Web site" vs "website"?
I always spell it "online," because I can't see "on-line" without pronouncing it "ondashline." However, I still use the hyphen in "e-mail," because it still modifies the word "mail." I know lots of folks have decided "email" is a distinct enough concept that it doesn't need the hyphen, but I'll stick with the tried and true for now.
And, for me, it's "web site." I don't see the value in capitalizing Web unless you're referring to "the Web" or "the World Wide Web" as a whole. And, under no circumstances would I use "website," or the even worse "homepage." (A "home page" is your starting point on the Web.)
Of course, when writing for someone else, I pretty much automatically write in their preferred style. TidBITS uses "email" and "Web site" and other oddities that don't match my preferences, and when I'm writing for TidBITS, that's what comes out of my fingers.