A few online archives store old Usenet messages. When the Usenet was first created, if you wanted to find some information then you posted a question to the a newsgroup and waited to see if someone would answer. Today, archives let you search previous postings going back months and even years to see if the question has been already discussed. These archives of online conversations form a fascinating historical record of Internet and popular human culture.
The first Usenet archive was called Deja News, and assembled a database of Usenet postings going back to 16 March 1995. Deja News was acquired by Google in early 2001 and renamed Google Groups, and after continued updating is now by far the best newsgroup archive available, with a database going back to 1982. The site also enables posting of messages to the Usenet, providing full featured interactivity.
The following resources provide newsgroup archives of one kind or another:
There are also a few older Usenet archives described on the historical archives page.
The web search section has advice on query construction that can also help you in searching Usenet archives.