Usenet is a wonderful service for finding and downloading digital media, giving you speed and reliability you won't find with other file-sharing options.
Usenet was originally designed as a bulletin-board service, and so there's a ton of text content available on Usenet, but once binary newsgroups made their way into Usenet, it quickly became a popular place to find any sort of files that interest you. A site called Newzbin started indexing the binaries available on Usenet and creating the NZB file format. When you download an NZB, you're simply downloading a file that points to files available on Usenet. Applications supporting the NZB format can use them to make downloading Usenet binaries a piece of cake.
There are two controversial issues attached to writing about Usenet: 1) the first rule of Usenet is that you don't talk about Usenet, and 2) it's commonly used to download copyrighted material.
Unlike most file-sharing services nowadays, Usenet is not peer-to-peer. While in rare cases you might get some poor level of access through your Internet service provider, you're going to want to pay for Usenet access that will actually prove useful. Currently I use Newshosting, several more (and potentially better) choices exist, such as GigaNews and Astraweb.
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