jwma is a Web mail implementation based on the JSP Model 2 architecture. It builds on standard Java APIs (Java Mail API, Java Server Pages, and Java Servlet API) and relies on some available open source technologies (Xerces, Castor, Jakarta-ORO). jwma is designed and implemented for use with an IMAP server. It allows complete control over the store (creating, deleting, and moving folders, mailboxes, and messages). It supports MIME messages, supports text/plain message processing (e.g. making plaintext URLs "clickable"), and supports automatic sent & read mail archiving. It features a trash mailbox, includes a small addressbook, allows simple configuration of its features, and can be used in parallel with other mail clients (like Pine or Eudora).
fget is a commandline tool for mirroring remote files via FTP. It is based upon the included FTP client library, whose API is designed to resemble the normal Unix API for accessing files and directories. This interface should make it very easy to integrate FTP support into other applications.
LibLZF is a very small, self-contained library that can be incorporated into applications where data compression would be nice but speed is more important. It can be used to add data compression in a painless way to any program. Likewise, a small and self-contained perl interface is available via CPAN (Compress::LZF).
This is a handy little library which provides a packet filtering mechanism based on the BSD packet filter (BPF). Most notably, tcpdump needs this to work, and there is also a perl module (still in beta) which can use this as well. In plain english, if you want to write your own network traffic analyzer, this is the place to start.