Some homeowners will put in an offer deadline when they are selling their home.
For example, a listing can say "all best and final offers are due Wednesday at 2pm". What you can do is put in a great offer a couple days before the deadline. Have the offer say the sellers have a 24-hour period to respond to your offer.
Now the sellers will be put in an interesting situation.
Do they take your great offer now, or stick with their deadline and have your offer expire, losing it forever?
You would be surprised how many sellers will accept the offer that came in early, go into escrow, and cancel their original plans that they had for the deadline.
All the buyers that were waiting to submit their offer at the last second will be really upset at the sellers... but you will get the house.
You will be the offer that got the deadline canceled!
And if they don't accept it the first time, just submit your offer again without the 24-hour shot clock.