Shelley Snyder, marketing coordinator for Intoxalock, said about 1.5 percent of the company's clients are voluntary, which includes parents imposing the setup on their young drivers.
"I know that isn't a lot, but it is growing at a slow, steady pace," she said.
One of Intoxalock's competitors, Guardian Interlock Systems, said its figures are slightly higher: 5 to 7 percent of clients are drivers voluntarily installing the equipment, with about 2 percent intended for use by teens.
Also gaining ground are clients using the system permanently after they've completed court-ordered monitoring — about 1 percent of Guardian's clients in 2010, compared with none the year before.
"We hope not to see these people again," said David Contreras, Guardian's vice president of operations. "It's the one product I've been associated with where I don't want to sell it to you twice."
If your drunken behavior tends to cause more remorse off the road than on, there's an app for that as well.
A handful — including "Don't Dial!" and "The Bad Decision Blocker" — will cut off your access to phone numbers for up to 24 hours, the former allowing you to name a friend as gatekeeper. Another app requires the answers to math questions before allowing you to send an e-mail, the presumption being it's really hard to do math while somehow impaired.
George Distler in Orlando, Fla., developed the BlackBerry app NOTXT n' Drive after a teacher at his daughter's high school was killed when a texting motorist — an older one — crossed a median and struck her car.
"I didn't even realize texting and driving was such a tremendous issue until I got into investigating it," he said. "I was challenged by my teenage daughters."