Same things as torrents. Apps, music. You name it, it's there. It's probably safer to use then torrents depending on what you download because only your ISP and your newsgroup service provider would be able to know what you have downloaded if they wanted to know in the first place.
Usenet are always used. Thanks to growth of binary retention, it's more secure and easier to find a file on newsgroups than on megaupload etc. Today the "best" provider has 1000days binary retention. It means that you can find a file during 3 years...and he won't be delete ! After 3 years, content change on server. You can compare Usenet providers on comparison engine. Hope it will help someone !