The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
Checky is a document validation and analysis extension for Firefox, Mozilla, and Netscape. It provides an easy-to-use interface to many free and commercial online validation and analysis services. It allows the user to validate, analyze, view, and inspect documents containing HTML, XHTML, CSS, RDF, RSS, XML, P3P, hyperlinks, metadata, and many more. It can check Section 508 and WAI compliance of documents with many helpful services. It can help in the design, development, and maintenance of accessible documents for a semantic web.
ArchView can open archive files online without downloading the whole archive, just like normal Web pages. It is very fast since it just fetches a small portion of the archive file from the server. It supports RAR and ZIP formats, and HTTP, FTP, and file: protocols. It can present XUL or HTML interface.