vxref provides integration of the xref tool into vim. The xref tool is a cross referencing and refactoring tool with a free version available that parses C and Java code, and a paid version that parses C++. vxref brings solid auto-completion (as opposed to all sorts of flakey varieties such as omni-complete) and accurate code browsing with scope information to vim.
eacc is a bash script that allows a group of people to share an encrypted, revision controlled file on a shared filesystem. Rather than store an encrypted file in RCS, eacc encrypts the RCS file and handles the decryption, check-out, check-in, and encryption steps automatically. The repository is encrypted using GPG's multi-recipient support, which allows each member of the group to use their own unique password. A typical use case would be to securely store sensitive information, such as password lists or account information, that is shared by a team.
ptee is a Unix shell tool similar to tee, but it allows you to invoke multiple sub-shells in parallel. Standard input to ptee is copied to both normal standard output and to each sub-shell running under ptee. Each sub-command is run concurrently and fed the same input. The output of each sub-command is thrown away, but any shell expression can be used, such as redirecting to a file. Note that there are some limits on ptee. The shell pipeline will only execute at the pace of the slowest sub-command; otherwise large amounts of data would have to be buffered. Also, the shell that ptee invokes requires 'sh'-like semantics, such as supporting the -c option.