rxvt-unicode is a clone of the well known terminal emulator rxvt, modified to store text in Unicode and to use locale-correct input and output. It also supports mixing multiple fonts at the same time, including Xft fonts, real transparency, and an optional embedded Perl interpreter that allows you to extend your terminal easily.
Libptytty is a small library that offers pseudo-TTY management in an OS-independent way. It was created out of frustration over the many differences of PTY/TTY handling in different operating systems for use inside "rxvt-unicode". It also offers session database support (utmp and optional wtmp/lastlog updates for login shells) and supports forking a proxy process after startup and dropping privileges in the calling process. It offers C++ and C-only APIs.
ggiterm is a software terminal emulator like xterm. However instead of X, it uses the GGI system for its rendering, which allows it to be displayed on anything from a framebuffer to multi-screens across networked hosts (including ordinary X sessions). It features multiple font formats, anti-aliasing, vt100 compatibility, and full internationalization.
xremote is a simple tool that lets you grab the mouse and keyboard of another machine and control them with your local mouse and keyboard. It creates a form of remote control of other machines. All mouse- and keyboard-actions on the local machine are forwarded to the remote display.
Conch is an SSHv2, Telnet, and VT102 implementation. It interfaces well with other Python projects such as Imagination, and includes an experimental console windowing library (Insults) and support for rudimentary line editing behaviors. A new implementation of Twisted's Manhole application is also included, featuring server-side input history and interactive syntax coloring.