There is no analogy to putty on a Unix platform, because its not just implementing the console interface, its also the SSH implementation as well, on Unix systems, its pretty easy to write a fully functioning terminal, because your just hooking into the existing pty system, so all you need to do is write (or borrow) a competent vt100 emulation, and make a UI.

PuTTY is great, honestly. It's not pretty, but neither is the windows console nor PowerShell.