abba is a FREE and public FreeBSD server, operating over weekends FRIDAY 20:00 - MONDAY 06:00 UTC time. I am now Waiting for 20 users to sign up to start the service for 24/7/365 days operation. You can add your username, name and e-mail address if you want to receive the shell, however you will still need to follow the sign up procedure like the rest - here.
Also check the list for other servers available, which run other operating systems.