PTT is still heavily used in Taiwan by university students. The numbers today might not be quite as high as the quote from Wikipedia below (due to the rise of Facebook), but the system is definitely still extremely active.
"PTT is arguably the largest BBS in the world with more than 1.5 million registered users. During peak hours, there are over 150,000 users online. It has over 20,000 boards with a multitude of topics, and more than 20000 articles and 500000 comments are posted every day."
There's at least about 20 Commodore 8-bit BBSs up currently, http://cbbsoutpost.servebbs.com/ and I'm sure more are out there as there have been recently developments in creating Hayes compatible internet devices.
If ssh is fine (and I can't think why you'd want to use telnet over ssh), then try Monochrome (ssh mono@mono.org, though I haven't used it myself in years). (They might not even have switched off telnet access yet, you never know.)
Oh yeah. Even better, there are still active GOPHER servers out there. Fire up Links and try hitting gopher://gopherproject.org. You won't be disappointed...
"PTT is arguably the largest BBS in the world with more than 1.5 million registered users. During peak hours, there are over 150,000 users online. It has over 20,000 boards with a multitude of topics, and more than 20000 articles and 500000 comments are posted every day."
http://en.wikipedia.org/wiki/PTT_Bulletin_Board_System