Hi Nervy Girl,
This is exactly how we found our house 11 years ago. We identified the neighborhood we wanted. We picked out the houses that met our wants and needs list, and the realtor wrote letters to these homeowners.
In a matter of days, we had our house. While the owners had been thinking about selling, the house never went on the market. They were happy. We were happy. It was a quick and easy experience for all of us.
Now, we are looking to buy again and using the same agent and same strategy. I think this strategy only works well if it is a serious buyer and if the message is conveyed sincerely to the potential sellers. It can't come across like it's a company that's looking to buy houses for cash or like a tactic to get an agent in the door for a potential listing.
Anyway, I don't think it's necessarily anything new, but it's really flattering that someone likes your house so much!
P.S. Our daughter just moved to Portland, and she LOVES it! Can't wait to visit her!