One of the things that plague photography, particularly long exposure photography is unintentional blurring of the image, often caused by knocking of the camera.
The best defense against blurred pictures is to use a tripod and follow the rule "hands off the camera". But how do you take a photo with your hands off the camera?
IR Remote Control
An IR remote control works pretty much the same as the remote you use to turn your TV on and off, except instead of turning the tele on and off the IR Remote Control for your camera allows you to take photos, and in some cases control basic attributes of the camera.
Problem with an IR remote control is that it doesn't work to well in bright conditions and it requires batteries as well as requires you to be roughly in front of the camera.
Shutter Release Cable
A shutter release cable is basically a device that connects to the camera and either electronically or mechanically manipulates the camera shutter button.
On the Canon EOS Rebel T3i it is an electronic remote that often has an intervalometer and other smarts built in.
These range from about $40 on ebay (some have a timer, others are just a button) all the way up to $70+ for the smarty pants ones that are wireless.
The funny thing is though, there isn't all that much to building your own and it doesn't cost all that much in both time and money.
Step 1: Disclaimer
I claim no responsibility if you break your camera building this accessory, some how electrocute yourself with the flash capacitor or kill a kitten or inflict or receive any harm or misfortune.
By undertaking this instructable you do so at your own risk.
Whilst I have made every best effort to insure this instructable is accurate given the fact I am not a professional there may be errors. If you find any please let me know either by PM or by posting on the instructable.
Now that we got the legal crap out of the way, lets get onto the building :)