actually it's netbsd running on a dual-cpu alpha 5305. but, yeah.
it's a server for unix shell accounts. meaning that you can log in remotely via telnet or secure shell and execute various and sundry unix commands.
from the page: users (free) !!! actually it's a dollar.
20mb home, 20mb web, 20mb mail
elm, pine, mutt, mailx, rmail, pop3
bash, ash, ksh, tcsh, rc, zsh, tclsh
http://yourlogin.freeshell.org
lynx, cgi and php4 scripting
icq, talk, commode chat, bboard
hundreds of UNIX utilities
arpa ($36 lifetime access)
100mb home, 100mb web, 100mb mail
one time donation for membership
all features of the 'users' account
private 'arpa' member server
telnet, ssh, ftp, ytalk, irc, snarf
gcc, lisp, perl, python, ruby, et cetera
access to additional memberships below
yep.