Niocchi is a Java crawler library implementing synchronous I/O multiplexing. This specific type of implementation allows crawling tens of thousands of hosts in parallel on a single low end server. Niocchi has been designed for big search engines that need to crawl massive amount of data, but can also be used to write no-frills crawlers.
SquirrelMail is a standards-based Webmail package. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages are rendered in pure HTML 4.0 for maximum compatibility across browsers. It has very few requirements, and is very easy to configure and install. It has all the functionality you would want from an email client, including strong MIME support, address books, and folder manipulation.
Pardus is an easy-to-use Linux distribution geared towards desktop users. It includes office tools (word processor, spreadsheet editor, presentation tool, etc.), Internet tools (Web browser, email, instant messaging, relay chat, etc.), multimedia and graphics tools (video player, music player, etc.), games, and lots of other applications.
mswatch is a command line program that keeps two mailboxes synchronized efficiently and with shorter delays by watching mailboxes to know when to initiate mailbox syncs. It is designed to work in conjunction with other mailbox synchronization programs and currently supports watching Linux (2.4+) hosted Maildirs (including Maildir folders, Maildir++).