Going for a PR in the deadlift? Then roll the bar toward you before you pull it up.
The principle behind this is simple: objects in motion tends to stay in motion; objects at rest tend to stay at rest. Once the bar is moving along the floor, it's easier to get it up. Here's a video of Magnusson's world record deadlift with the roll before pulling:
It's like rocking a car stuck in the snow: you move it back and forth to get it moving and then it goes. Essentially, get into deadlift position, roll the bar out in front of you and then roll the bar back towards you. When the bar hits your shins, pull it up and deadlift like normal.
There are some other additional benefits to rolling the bar before lifting it, including greater use of the stretch reflex, something generally missing in the deadlift. This method can also help get the bar closer to the shins (which is key in a deadlift), or get into a better starting position. Rolling the bar in might also help activate the lats.
It takes a while to get used to. It might take 5-10 deadlift sessions before you really start getting comfortable with it. If you time it wrong, you'll start pulling before the bar is in close enough, putting you in a worse position than where you started from.
To practice this you have to perform stop reps, which may not work depending on your lifting style and what you're trying to work on. It doesn't work with rack pulls and the like, and the "dip, grip, and rip" style deadlifters will likely find themselves thrown off their game.