In the Seinfeld episode "The Reverse Peephole", Kramer and Newman reverse the peepholes on their apartment doors so that they look inside the apartment rather than out. When asked what purpose that could possibly serve, they bring up the possibility that some lunatic could be waiting inside to ambush them with a sock full of pennies. At the end of the episode, a minor character gets ambushed in this exact way by another character who mistakenly thought that his wife was cheating on him with the first character. "He should have had a reverse peephole..."
From The Simpsons: When Homer and his buddies become a vigilante force because the police can't catch the Classy Cat-Burglar stalking the neighborhood, Jimbo joins. He's told that his Weapon of Choice should be sack full of door knobs (a news anchor interviewing Homer later mentions that beatings with such a weapon have skyrocketted).
In the Discworld novel Sourcery, Rincewind attempts to fight the Sourcerer with a half-brick in a sock. He later fills his other sock with sand in the Dungeon Dimensions.
Coin: “You're going to fight them with a sock full of sand?”
Rincewind: “No, I'm going to run away. The sock full of sand is for when they follow me.”
From Mallrats: "Phase one: First you take a run at La Fours with a sock full of quarters. I'd do it, but I pulled my back out humping your mom last night. Nootch. Okay, you clock him on his headpiece and knock his ass out cold. That's when phase two kicks in. I attack the structure Wolvie-Berzerk style, and knock out the ****in' pin and bickety bam, the mother****er is rubble. Hence, no game show."