bash argsparse is a high-level argument parsing library for bash. Its purpose is to replace the option parsing and usage describing functions commonly rewritten in all scripts. Its features include automatic help message generation, user input checking (type checking, enumerations, etc.), and option properties (mandatory options, option aliases, options excluding each others, etc.). It is implemented for bash version 4. Prior versions of bash will fail at interpreting the code.
icli is a command line interface to the Icinga monitoring software. You can use it to list service/host status with many filtering options, schedule rechecks, and acknowledge service problems. Basic support for viewing the command queue and scheduled downtimes is also present. It is largely compatible with Nagios.
imapsync is a tool for facilitating incremental recursive IMAP transfers from one mailbox to another. It is useful for mailbox migration or backup, and reduces the amount of data transferred by only copying messages that are not present on both servers. Read, unread, and deleted flags are preserved, and the process can be stopped and resumed. The original messages can optionally be deleted after a successful transfer.
hashl creates a database with partial file hashes. It is useful for checking if you already have a copy of files before transferring them over a slow network. It does this by hashing only the first few MiB of every file. This gives it a huge speed advantage at the cost of possible (though pretty improbable) false positives.