WebXACT: Homepage analyzer.

Very detailed IP-Whois database

Domain name availability

German page with internet search hints

SELFHTML

List of PHP webmailers

List of XMPP clients

Mindquarry installation

MXtoolbox: To doublecheck your the MX-record of your DNS entries.

Apache: Apache 2.2 docs.

Java applets - How to sign a java applet: This is required e.g. if you want your java applet to be able to access your local filesystem.

woorank: A very nice online-tool to analyze your site.

Dan Walmsley: Now to configure the Nginx webserver to run concrete5

Anilcetin.com: Online converter of Apache htaccess-rules to Nginx.

Loadimpact.com: A nice site that provides for free a simple stress-test for your site.

OpenSSL certificates for Apache in Gentoo

Name based virtual hosts for Apache in Gentoo

Install an ejabberd server with jwchat proxied through Apache

phplens: Performance tuning for PHP & Apache.

gzip-test: Online tool to check if site compression is on.

pingdom tool: Online page speed test.