Do you carry around stuff that's way too valuable to trust to a standard luggage lock? Like piles of gold, nuclear access codes, or compromising photos of members of the Bush administration? If so, you'll need an intense lock. A lock that won't let people access your stuff, and one that'll let everyone in a 5-mile radius know if someone tries.
The Lock Alarm is such a lock. It's got a 100-decibel alarm on it, so if someone tries to get into your stuff it will deafen them with sound or at least scare the living crap out of them. Sure, it's overkill for basically anything most folks would want to protect, as normal locks are just fine, but if you're really paranoid $25 isn't that much to spend to get some peace of mind.