Live View: Manual focus on a tripod.

I steer clear of manual focus in part because I do not have perfect eyesight (I can't shoot with glasses on and the dioptre adjustment does not go far enough) and because the viewfinder is too small for me to do this effectively (others may not have the same problem). However, there are certain situations where having manual focus capability would be fantastic including in macro photography and also in a studio portrait environment. In both of these situations the camera is typically mounted on a tripod and the subject is not moving meaning that you can take your time to focus properly. Also, in both of these situations you often end up with or choose to have a shallow depth of field and it is critical get get a specific part of the composition in focus (e.g. the eyes in a portrait).

Live View gives you the ability to focus manually while being able to see the picture on the nice big bright display on the back of the camera. Furthermore, you can zoom in to the image to ensure that you get the critical part of the picture in to focus.

When in Live View it is typically best to use Live View focus mode (as opposed to quick mode or face detect). You can move your focus point using the joystick and use the + and - buttons to zoom in and out. The video below explains this in more detail.