cache stampede prevention strategies tho

We've been running into some problems with cache stampedes lately, particularly when traffic spikes. Basically, when a popular item's cache times out, a bunch of requests all hit the origin server at the same time, and that really bogs it down. So, what are your usual ways to stop this from happening? Are you guys doing things like probabilistic early expiration, distributed locking, or something totally different? I'm just really curious to hear what actually works out there.