The computer mouse is likely the most used input method for cursor control in computer desktops--and for good reason. The device is easy to work with and is precise. Over time developers have further improved the design--the old-style ball has been replaced with laser, there are new functions due to buttons and improved scroll wheels, there are wired and wireless versions, etc. The mouse is not perfect, and there can be improvements. Below I list several devices that could replace the mouse.
One disadvantage of a mouse is that it requires us to take one hand off the keyboard, which over time could waste time--but of course the uses are many and in the case of many cursor manipulations the mouse is still the better choice for most applications.
There are ideas of replacing the mouse with something superior. Depending on the intended function there may be devices that are better than a regular mouse. Below I list a few of the available mouse replacement systems--some that are just "out there" as ideas and some that are actual products.
Flow - Uses gestures and touch.
Touchpads - These devices work well with laptops. For desktops they can work in cases in which precision is not necessary. The surfaces vary, but they do feel quite well to the touch. However, precision may be the biggest shortcoming of touchpads; perhaps software revisions need to take place.
Eye Tracking systems - I have always envisioned that the eye could serve as a form of cursor control. It could be done, but it requires a lot of study of the eyes and programming to correct the rapid eye shifts that occur--also it seems that the current software does not support interaction well enough for this to be effective. With existing technologies, such as the Eye Tribe Tracker and the Tobii EyeX, eye tracking is nowhere near of what a computer mouse can achieve.
Eye Tracking post (mostly ideas without actual experience)
Eye Tribe Tracker and Tobii EyeX are likely to be the dominant devices as of right now.
My experience with The Eye Tribe development kit.
Mind-based systems. - The mind gives instructions to muscles, so in theory it could be used as a faster method of controlling systems. However, the problem is that our technologies for interpreting what the mind wants is not precise enough. There is simply too much that still needs to be worked on. Furthermore, it seems that these systems also need to be trained. Emotiv is one of the many available devices.
TrackPoints - These are popular in ThinkPad devices, although they are present in other companies. Generally the TrackPoints are either loved or hated. Some people this joystick like device more so than touchpads, however some people detest them so much that they remove the little rubber top as to not use it. Personally, I prefer it for small screen devices. The advantage of the TrackPoint is that it is located directly on the keyboard, therefore you do not have to remove your hand in order to manipulate the cursor.
More PC Mouse Replacement Devices