http://img242.imageshack.us/img242/9489/cablej.jpg
what is it for??? I’ve seen this cylindrical thingy on all sorts of cables, most notably USB and VGA, does it have a purpose? is it a resistor of some sort?
a fantastic question but i don’t have anything like that 
It’s very likely to be a fuse.
That is called “choke”. It used to reduce EM interference on data passing through cables.
Choke - Wikipedia(electronics )
cool thanks!