Remote controls are a great addition to your camera bag. For me, the greatest advantage for these devices is that you can take a picture without inducing any camera shake during long exposures.
You can buy commercial remote controls, or you can build one yourself that has more character.
There are a lot of sites online that describe the actual construction so I will refer you to one of them for the construction details.
A good site to use is: http://picsbylance.com/?p=1443 (link no longer works)
I made several changes in the construction to meet my requirements. Since I wanted this remote to do long duration “bulb” exposures I did not need the focus/exposure button. Since these would be for long exposures I used a toggle switch instead of the push button for the shutter.
The cable I used was from a 3.5mm standard stereo mini-plug and I left a junction in the middle so I could add an extender cable if I needed more distance from the camera.
I used an old 35 mm film container for the switch box for fun (it actually feels good in the hand).
Jim