ZOC is a well known telnet/SSH/SSH2 client and terminal emulator. It's functions (like tabbed sessions, typed command history, scrollback, multiple window support, etc.) and solidly implemented emulations make it the preferred tool for people who have to access Unix shell accounts from a Windows or Mac OS X platform. Linux admins will feel like sitting on their native console with ZOC's support for colors, meta-keys and local printing.
Besides that, it features widely used terminal emulations like vt102, vt220 and several types of ansi and not so widely used ones like TN3270, TN5250, Wyse, TVI and Sun's CDE. ZOC also features major file transfer protocols like X-, Y- and Zmodem as well as Kermit and SCP. All these are offered in solid implementations which leave nothing to be desired.