Commodore 64 BBS · real C64s: telnet finzshop.duckdns.org port 6400
Finz's Shop is a hobby bulletin board system (BBS) for Commodore 64 fans, the kind people dialled into with a modem in the 1980s. It runs on a Raspberry Pi. Callers leave messages, chat, swap C64 files and play games. The screen above is the BBS itself, shown the way a C64 would draw it.
Type NEW at the handle prompt to sign up. Your handle and password are only for this board. Make up a new password for it: don't reuse one from another site. The BBS never asks for your email, bank, card or any other account details, and it isn't linked to any other service.
Use a WiFi modem (or an Ultimate's built-in modem) and a terminal program such as CCGMS, and call finzshop.duckdns.org port 6400.