Keyboard shortcuts can save you a lot of time, especially if you do a task many times. Google web applications have shortcuts and it's a good idea to learn them. Don't worry, most of them are pretty intuitive.
Let's start with Gmail. If you press "c", you'll compose a new message; if you use "r", you'll reply to the current message. You can move to the next conversations using "k".
In Google Calendar, you can create an event using "c" or if you want add the event quickly type "q". View your agenda by pressing "a".
Google Video has very simple shortcuts: press space to pause a video and once again to resume it, use right/left arrows to go forward/backward in the video and up/down arrows to change the volume. To mute the video press "m".
In Google Maps, you can use the arrows to move in the map, "+" to zoom in to the map and "-" to zoom out of the map.