3. Think.Com, registered May 24, 1985
Thinking Machines Corporation was a former supercomputer manufacturer when it was founded, but by 1997 the company was selling data mining software on the third dot-com in history:
By 1999, the company had been acquired by Oracle, and by late 2000 Think.com was a free hosted Web service for public school students that included email, home pages, collaboration tools and more.
Today, Think.com redirects to Oracle's thinkquest.org, which is billed as "a learning platform where teachers and students create learning projects."
(March 15 isn't the only important anniversary this year. Check out PCWorld's 25 Geeky Silver Anniversaries to Celebrate in 2010.)
4. MCC.Com, registered July 11, 1985
Founded in 1982, Microelectrics and Computer Technology Corporation was a computer industry consortium specializing in research and development. Among MCC's numerous research projects were technologies like advanced vision systems, collaboration management infrastructure, and server and network technology.
By 2000, however, MCC was looking at spinning off all or part of its major projects into individual companies. MCC was eventually dissolved, but here's what it looked like in late 2000:
Today, MCC.com is basically a parked domain with no real content, and owned by a Shanghai-based company. The site has a search engine powered by searchmagnified, which has been flagged for suspicious behavior by security firm McAfee.