Linux HTTP Servers

Apache mod_ssl module to support open SSL (Secure Socket Layer)
Apache JAVA Projects- Jserv: Java servelet engine
Apache-userdirldap - Enables Apache to look up user home directories from an LDAP server for use in UserDir (~username)
Apache auth_ldap - support for LDAP over SSL, and a mode that lets Microsoft Frontpage clients manage their web permissions while still using LDAP for authentication.
Apache mod_frontpage - Improved nodule which replaces the Apache-FP patches and module supplied with the Microsoft FrontPage Server Extensions available from Microsoft and Ready-to-Run Software.
Apache mod_atrack - module adds advanced user tracking functionality. It reduces the annoyance of sending multiple cookies to a single user and allow more intelligent analysis of collected data.
Apache mod_auth_ldap module allows Apache to authenticate users against an LDAP directory.
mod_auth_ldap for Netscape or OpenLDAP servers (Good HowTo)
Apache mod_auth_nds module allows users to authenticate using Novell's NDS.
Apach mod_auth_pop3 module for POP3 authentication.
Apache mod_auth_radius module for authentication agains a radius server.
Apache mod_auth_smb module to authenticate against SMB servers (like Windows NT and Samba)
Apache mod_auth_tds module authenticates using information found in a TDS compliant database such as Microsoft SQL Server and Sybase.
Apache mod_backhand module for cluster load balancing
Apache mod_bol module for authentication with a MySQL user database
Apache mod_cgisock module to 'cut loose' the CGI script from Apache memory space
Apache mod_cgi_debug module to help debug CGIs, servlets, and mod_perl and PHP scripts.
Apache mod_color module performs text file syntax coloring of source files. Preconfigured for C/C++ ("c-source"), yacc/bison ("yacc-source"), lex/flex ("lex-source") and perf/gperf ("perf-source").
Apache mod_dav module enables Apache to understand the "Distributed Authoring and Versioning" (DAV) protocol (extensions to HTTP) defined by RFC 2518. DAV is intended to replace proprietary authoring protocols such as those used by Frontpage or NetObjects' Fusion, but is also a complete set of protocols for manipulating a webserver's files and directories, and their properties.
Apache mod_dynvhost module for dynamic virtual hosting on the fly.
Apache mod_extract_forwarded module to transparently modify a connection so that it looks like it came from the IP behind a proxy server rather than the proxy itself.
Apache mod_fastcgi module to provide high performance and cgi persistence without the limitations of server specific APIs.
Apache mod_frontpage module to support FrontPage server extensions.
Apache mod_hosts_access module allows you to use hosts.allow and hosts.deny files to configure access to your Apache webserver.
Apache mod_jive module to "jive" coresponding text and html pages.
Apache mod_layout module to provide Footer and Header directives to be included in output from other URLs. Used to wrap documents for a standard look and feel for a site. Supports mod_perl, PHP and Apache JServ.
Apache mod_log_spread module to provide an interface for spread to multicast access logs. Solves the problem of collecting consolidated access logs for large web farms.
Apache mod_ntlm module to authenticate against NTLM (used in Microsoft based Intranets. Password validation is done through Windows NT or Samba machines over TCP/IP.
Apache mod_perl module is a persistent PERL interpreter embedded in the server which avoids the overhead of starting an external interpreter and the penalty of Perl start-up time.
Apache mod_proxy_add_forward.c module that allows you to get the client IP back on the proxied host.
Apache mod_relocate module for creating virtual documents from offsite links and logging click-through transaction trails.
Apache mod_repository module which turns Apache into a content storage system. This can be used to create content servers which are abstracted from the filesystem. Files can be placed, retrieved, and deleted from the server.
Apache mod_roaming module allows you to use the Apache webserver as a Netscape Roaming Access server. This allows you to store you Netscape Communicator 4.5 preferences, bookmarks, address books, cookies etc. on the server so that you can use (and update) the same settings from any Netscape Communicator 4.5 that can access the server.
Apache mod_text module to rewrite legacy ASCII text into limited HTML. It will recognize most URLs (both explicit and implicit) and create hyperlinks.
Apache mod_throttle module to provide virtual server throttling of bandwidth.
Apache mod_ssl - Apache interface to SSL - Manual

Links:

YoLinux.com Web Tutorials:

YoLinux.com Apache Configuration Tutorials:
- Apache, DNS (bind), FTP
- Apache logon authentication and web site protection - Add a login to your web site. Authenticate using a password file, NIS, LDAP or MySQL.
- Redirect a web page or web site/domain request to the proper web site/domain
- Linux Internet Security and Configuration
- Tomcat: Java servlet server
- My Photo Gallery - Online photo album
Audio Streaming Server Set-Up
Real Video Server Configuration
Learn XHTML in two minutes - Look and learn.
Learn HTML in two minutes - Look and learn.
Web Tricks - HTML, Javascript, e-mail
Setting up a web page counter for display on the web page
Server Side Web Page Scripting Tools - facilities for the creation, publishing and management of web content.
YoLinux Tutorials on Dynamic Content: