Huntor is a full-featured command line Bittorrent client. It currently has no GUI. This client focuses on being run in the background, such as on servers. It is highly customizable. Its disk storage layout makes it easy to incrementally rsync the data to a different machine while downloading.
Search::Xapian is a Perl XS frontend to the Xapian C++ search library. It is a fairly complete wrapper: most features of the Xapian library are made available for use from Perl. Xapian is a highly adaptable toolkit that allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model as well as a rich set of boolean query operators. It's fast and scalable to hundreds of millions of documents.
ComicMan downloads Web comics from the Internet to your hard drive. It remembers the last download for each title, so you won't get duplicates from running it multiple times. The application itself is a command line tool, but it comes with a graphical configuration tool and an editor for making new Web comic configuration files.
Config::Maker takes a file with data in simple hierarchical format (similar to BIND and DHCP configuration files) and several templates, and produces the text by filling in the values. It is mainly useful for creating related configuration files. It can be used to generate firewall configuration scripts, DNS zone files, DHCP configuration files, a reference from a single file with all users and machines, etc. It's useful when you are not satisfied with keeping information synchronized in several places, but don't want something as complex as cfengine. Snippets of Perl can be used if all else fails.