Gmail
Right about now I suspect everyone is learning what a lot of postgrad computer science students learn in their first week: A computer network is a system where your work can be completely buggered up by a computer you’ve never heard of, in an office you have no access to, run by someone you can’t contact, but which you can’t replace or route around 😀
Well, that or they’re learning to use mutt and IMAP and reading their google email that way, which still works fine 😀