Zenity is a tool that allows you to display Gtk+ dialog boxes from the command line and through shell scripts. It is similar to gdialog, but is intended to be saner. It comes from the same family as dialog, Xdialog, and cdialog, but it surpasses those projects by having a cooler name.
libssh is a C library to access SSH services from a program. It can remotely execute programs, transfer files, and serve as a secure and transparent tunnel for remote programs. Its Secure FTP implementation can play with remote files easily, without third-party programs other than libcrypto (from OpenSSL) or libgcrypt.
MT-write is a binary patch for multi-threaded writing. It comes in the form of a shared object that can be preloaded to programs like tar to make their write operations multi-threaded. Multi-threaded writing can improve performance on RAM based filesystems and highly scalable filesystems with multiple spindles.
Shell Flags (shFlags) is a library written to greatly simplify the handling of command-line flags in Bourne based Unix shell scripts (such as those run with bash, dash, ksh, sh, and zsh). Most shell scripts use getopt for flag processing, but the different versions of getopt on various OSes make writing portable shell scripts difficult. shflags instead provides an API that doesn't change across shell and OS versions, so the script writer can be confident that the script will work.
Ccide reads C, C++, BASIC, or bash source code containing embedded decision tables from stdin, expands the tables, copies the remaining statements, and forms a compilable C or C++ source module, executable bash script, or interpretable BASIC program. Erratic side effects are avoided by evaluating all condition expressions at exactly the same time, and by performing all evaluations and actions in the original sequence.
Shellp is a shell helper library. It is intended to make it easier to write commandline-based applications. Commands are easy to define, and can be entered interactively or by reading from a file or standard input. If a graphical workspace is available, a Qt-based interface can be used. Otherwise, an ncurses-based one may be used. If the platform doesn't support that, either, reading from a file is still an option.