ChronoMouse displays a small clock that follows your mouse cursor, showing the current hour. This keeps the time always in your field of view without needing to look away from your work.
Hold the Option (⌥) key while moving your mouse to display minutes instead of hours.
ChronoMouse automatically enables "Launch at Login" on first run. You can toggle this setting by launching the app again while it's already running—this opens the Settings window.
Yes. ChronoMouse is open source and free to use.