Alkaline is a full-featured standalone search and index server. The spider is a fully remote indexing daemon which includes support for all standards like robots.txt and "skip" meta tags, and allows multiple distinct configurations and search groups (searching many different sites from your server), including complex regexp indexing paths, authentification, filters for various document formats, XML-based online management and statistics, mrtg-compatible perf numbers, and more.
Kannel is a WAP gateway. It attempts to provide this essential part of the WAP infrastructure freely to everyone so the market potential for WAP services, both from wireless operators and specialized service providers, will be realized as efficiently as possible. It also works as an SMS gateway for GSM networks. Almost all GSM phones can use it to send and receive SMS messages, so this is a way to serve many more clients than just those using a WAP phone. Kannel was among the first WAP gateways to be certified as WAP 1.1 compliant.
mod_backhand is a load balancing module for Apache. It provides per-request HTTP redirection within a heterogeneous Apache server cluster. Each request is processed and run through a set of "candidacy functions" to determine which server is best suited to respond. The request is then proxied to that server. Facilities are in place to allow you to write your own dynamically loadable decision making algorithms. Everything about the request and the current availability of resources can be used in the decision-making process.
NatACL is a Linux firewall group policy controller for intranets and Internet. Using a internal DHCP server, it can force users to use a DHCP client, and you can block static IPs. It will bind an IP to a MAC address and enforce this usage. You can control groups that can see each other with intranet policies, or control who has access to the Internet. It also has an option to force users to authenticate themselves over the Web before accessing the Internet.
mod_sphinx is an Apache module which intercepts output bound for the client, whether it be from files served by the same Web server, files sent via reverse proxying, or files delivered by transparent forward proxying (outbound proxying, as in your browser's proxy setting). It opens the text and replaces a word with another word or phrase. When in regular proxy mode, it cannot modify SSL content since Apache cannot decrypt that (it would be a protocol violation).
mod_vhs is an Apache 2.2+ Web server module allowing mass virtual hosting without the need for file-based configuration. The virtual host paths are translated from any database supported by mod_ldap or mod_dbd at request time from MySQL, LDAP, PAM, or a system password file. PHP security can be basically auto-configured from the database using this module. Requests are cached by mod_ldap when configured.