AA-lib is a low level gfx library just as many other libraries are. The main difference is that AA-lib does not require graphics device. In fact, there is no graphical output possible. AA-lib replaces those old-fashioned output methods with a powerful ASCII art renderer. The API is designed to be similar to other graphics libraries.
conexus is a generalized C++ I/O library that includes network support for IPv4 and IPv6 sockets, serial/TTY communications, kernel message queues, pipes, and files. Objects use sigc++ for signaling property changes and other information. Sub-libraries include conexus-gtkmm (provides a set of gtkmm widgets), conexus-dbus (provides dbus support for endpoints), conexus-nspr (provides NSPR endpoints), conexus-nss (provides NSS endpoints), and conexus-ssl (provides OpenSSL endpoints).
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.
ROTE is a simple C library for VT102 terminal emulation. It allows the programmer to set up virtual 'screens' and send them data. The virtual screens will emulate the behavior of a VT102 terminal, interpreting escape sequences, control characters and such. The library supports ncurses as well so that you may render the virtual screen to the real screen when you need to.