Back in the early 2000's I worked for a company that was was hired (via intermediary law firms) by publicly listed companies to investigate pump and dump schemes on Yahoo message boards (you might call that the "Reddit of the early 2000's"). It involved a lot of web scraping Yahoo with Perl (specifically LWP) and then lots of analysis by humans with some help from automated tools. For example, if you plotted a histog…
Lexis Nexis has been around a lot longer than that. By "online" do you mean web accessible?