Sometime you have no choice but to run wires under the carpet; you might have finished rooms above and/or below where you need to run networking, speaker, or other low-voltage wiring. You’re not going to get very far just trying to push the wire under the carpet — that’s where an under-carpet snake comes in handy.
This snake from B.E.S. is 25 feet of flat annealed stainless steel. You fish the rounded end under the carpet, thread the wire through the hole at the tip and secure it, and pull the wire back under the carpet. The snake comes in its own curled PVC case, which stores the tape and keeps it coiled and compact.
This snake will bite you for $40 to $60 depending on where you look.