I guess I would date myself, but: - syntax highlighting in text editor - tabs in browsers (in my case that was Firefox before it was called Firefox) - DVCS,

I guess I would date myself, but: - syntax highlighting in text editor - tabs in browsers (in my case that was Firefox before it was called Firefox) - DVCS, I've started with Bazaar then moved to Git (of course). Used VCS (painful) and SVN (less so) before that. - REST APIs and discovering Sinatra framework to write them. - Rails. First time I saw famous "write blog in 15 minutes" my head was blown.