The patent troll company Innovatio IP Ventures sent over 14,000 letters to hotels, coffee shops and supermarkets demanding licensing fees because these businesses used wireless network products which apparently infringed 23 of their patents. Cisco, NetGear and Motorola Solutions took the company to court and eventually reached a settlement of $2.7 million with Innovatio.
WD-40 doesn’t have a patent because the company didn’t want the ingredients to be public knowledge. Instead, the formula is protected as a trade secret.