libapache2-mod-scramble-ip is an Apache 2 module that works like mod_removeip, but instead of just overwriting the IP address with 127.0.0.1, it encrypts the IP address. This way you always get an IP address to work with (in scripts, etc.) and have the ability to use tools like awstats to analyze your logs. It's in alpha status, but working on some Apache 2 servers, and the 'cost' (load) should be small and reasonable.
Auth MemCookie is an Apache v2 authentication and authorization module based on a cookie authentication mechanism. The module doesn't do authentication by itself, but verifies if the cookie used for authentication is valid for each URL protected by the module. The module also validates whether the authenticated user has authorization to access the URL. Authentication is done externally through an authentication form page, and all authentication information necessary to the module is a stored in memcached.
mod_sesehe is an Apache module that disguises and removes the "Server: " HTTP header from responses. This allows you to hide certain information about the server. This also allows more accurate information to be provided if Apache is configured as a reverse proxy and a malformed request is received. Although sending the Server header in HTTP responses is not defined as a MUST in RFC 2616, the Apache HTTP Server does not otherwise allow you to disable sending this header via its configuration.