This page has check boxes to search for people, software, and other information by easy to select categories. Searches the Web, gopher, and Usenet. If it is on the net you can find it here. Easy to use, I start here for newsgroup searches. Excludes .alt, .soc., and .talk.
Messages base goes back to as much as one year.
Good ways to limit searches. You can search for sale Newsgroups here. Search up to 30 days of prior newsgroup postings without regard to category. Tends to give a result that requires a lot of wading through. See above for more complete description.