I've often found that the default Emacs frame title is a little bizarre. emacs@host Seems a little useless at describing what's going on in the actual window in my opinion, and I believe the space could be put to much better use. Perhaps it's designed for environments where X11 forwarding is common practice, or where GNU Emacs shares a system with XEmacs.

Taking inspiration from both Emacs and Firefox, I came up with a frame title format that I think is much more useful.

(setq frame-title-format '("%b@" (:eval (or (file-remote-p default-directory 'host) system-name)) " — Emacs"))

Instead of emacs@hostname, I use buffer-name@buffer-host — Emacs. Here buffer-name is the name of the currently focused buffer, and buffer-host is the host on which the buffer's file resides. This means that if you're connected over TRAMP to another host, the remote host's name will be displayed in the frame title. I then added — Emacs at the end, so that it's still obvious which program owns the window.

It's possible to customize the title a lot more, but this seems to be a good middle ground for me. frame-title-format uses the same formatting template as mode-line-format, so you can check that variable with describe-variable too see all the formatting options available.