Is there any way to remote control a Canon Rebel T3i 600D from the computer, for example to take shots like every x lapse or something like? I also need the software to do it, I'm looking for a good software that works.
Here is a link to a video series from Canon's Digital Learning Series that teaches about using the bundled software from Canon to shoot tethered to your PC. There is a section on automated interval sequencing.
A free tethering solution http://digicamcontrol.com/ which support Nikon and Canon cameras [Disclaimer: I'm the developer]
I've used DSLR remote pro in the past but the price is a bit steep at $175
Sample download the newest software from the cannon web: Reference: http://photo.tutsplus.com/articles/post-processing-articles/simple-tethering-for-canon-and-others/
There's also Helicon Remote software: http://www.heliconsoft.com/heliconsoft-products/helicon-remote/