Not at this time, but China and Asia sure are using them for websites, as is the rest of the world. China is big buyers on numerics, primarily because they were shut out of the .com market several years ago and they don't have much of a choice. And also numerics mean words to the Asian culture, so they are really big buyers. The U.S folk currently have around 94 mill .coms I believe (might include .net), and Asia / China which is much larger only has around 10 mill, so numerics are very important for them with regard to websites and .coms. Therefore, the buyers market is with China and the rest of the world. So the U.S. buys, and sell to the rest of the world like any other type of international exports, so to speak.
With Americans it's a little different and they hold a collector type of value as the market is limited and each numeric is unique. When the internet came around, it destroyed collectibles in general worldwide as the internet connected people, so people who thought they had rare coins, stamps, baseball cards, etc.... found that their collectible wasn't so rare anymore and there were many around the world. Baseball cards and coins that were once rare and worth a couple thousand, were suddenly worth $5 as there were many worldwide. So to a lot of people, numerics are almost collectibles like a modern day coin collection. It's really one of the only "collectibles' around, and I believe people "need" things like that. To me anyway, I just like collecting them at the moment.
Having said all of that, perhaps they will become websites of the future down the road 5 - 10 yrs. Who knows. I know American Express uses 1-800-The Card for their website. I also have my 800 number for my company forwarded to my website and I also put it on letters I send out as a secondary URL.