I need to make visible laser beam and detector for crossing this laser (like in spy movies :). Can I use laser like this http://www.sparkfun.com/products/9906 and simple photoresistor connected to arduino? Distance between photoresistor and laser will be around 5 meters.
You might want to look at the below kit.
make visible laser beam
Be advised, that laser (dispute what they show in movies) usually is not visible in clear air, untill it hits some substance which make it disperse around (smoke , fog, dust). Photoresistor approach should works, only you'd need create high pass filtering in software to make it reliable in different lighting conditions.