There is a number of telnet bbs's still running today! They have become telnet-based so they can be reached from the internet (and not by actual dialing). Some of them are using the original software of that era and there are such listings available. Most if not all of them exist for demonstration purposes only of course, there is no meaning or useful functionality in them apart from the fact that you can live once more the original experience.
In fact I have myself resurrected the bbs I used to have in the early 90's, adopted it to modern times (removed fidonet etc) and made it available for easy access via a flash plugin on a web page, so that not even a telnet client is needed. I'm nor sure if it's ok to write the link, although to be honest I don't see why it could hurt anything.