geekyhttp://olduse.net/
There are 2 options for accessing it, either a web-based command-line interface, or a client program that speaks NNTP (Thunderbird is a good one for that, and is what I'll be using). The "command-line" interface on the main site isn't very stable at all, but there are mirrors that are better.
You can't post anything, as it's a one-way tunnel through time, but there's plenty there to read. They'll be doing this for the next 10 years, so it'll be interesting to see it as it develops (er, developed).
