Wocvim is a WoC client for Vim. WoC is a protocol which enables the use of hyperlinks in plain ASCII texts. The links can point to local or remote locations. The protocol is specifically designed to support source code, but it can be used in any text. For source code, it's also possible to use ad-hoc tag generators like cscope and ctags.
rvi is a wrapper script which gives you an easy way of integrating RCS with your existing vim/vi work environment. Simply use "rvi filename" instead of "vim filename", and the file will automatically be checked into revision control, and the changes you made after the edit will be displayed each time you finish editing.
Plash is a sandbox for running GNU/Linux programs with minimum privileges. It is suitable for running both command line and GUI programs. It can dynamically grant Gtk-based GUI applications access rights to individual files that you want to open or edit. This happens transparently through the Open/Save file chooser dialog box, by replacing GtkFileChooserDialog. Plash virtualizes the file namespace and provides per-process/per-sandbox namespaces. It can grant processes read-only or read-write access to specific files and directories, mapped at any point in the filesystem namespace. It does not require modifications to the Linux kernel.
The Heirloom Toolchest is a collection of standard Unix utilities. It was derived from original Unix material released as open source by Caldera and Sun, and contains multiple versions of each utility corresponding to SVID3/SVR4, SVID4/SVR4.2MP, POSIX.2-1992/SUSV2, POSIX.1-2001/SUSV3, and 4BSD (SVR4 /usr/ucb). It processes lines of arbitrary length and in many cases binary input data, supports characters in UTF-8 and many East Asian encodings, and contains more than 100 individual utilities including bc, cpio, diff, ed, file, find, grep, man, nawk, oawk, pax, ps, sed, sort, spell, and tar. Extensive documentation is included.