Statuscodes
https://de.wikipedia.org/wiki/HTTP-Statuscode

Links
https://subgraph.com/vega/download/index.en.html - Vega Vulnerability Scanner
http://popuri.us/ - PageRank / link popularity check
http://validator.w3.org/ - W3C Markup Validation Service
Bluefish - HTML / PHP editor for Linux, supports direct edit on FTP
http://ckeditor.com/demo - Online WYSIWYG Editor
SELFHTML - HTML / PHP reference
seitwert.de - shows Google PageRank and statistics for a URL
http://www.meb.uni-bonn.de/html_tutorial/zeichen.htm
http://www.archive.org/ - The Wayback Machine
http://www.magentocommerce.com/ - eCommerce Open Source software
http://en.wikipedia.org/wiki/List_of_web_analytics_software
http://www.ispcp.net/ - Multi Server Control and Administration Panel
http://www.robertnyman.com/ajax-suggestions/demo.htm - AJAX Suggestions module
http://www.imavex.com/php-form-builder-class/examples/form-elements.php - PHP Form Builder Class
http://www.xaranetblog.de/2008/08/02/apache-php-und-mysql-auf-utf-8-umstellen/ - Apache, PHP und MySQL auf UTF-8 umstellen
http://de.selfhtml.org/html/referenz/zeichen.htm - HTML character reference
https://securityheaders.io/ - browser security scan

CMS systems
http://www.liferay.com/ - Java CMS Portal

Search engines
Google URL registration - Add your URL to Google index

Create Google Static Maps
http://gmaps-samples.googlecode.com/svn/trunk/simplewizard/makestaticmap.html

SSL
https://letsencrypt.org/
http://www.startssl.com/?app=39

Disable browser caching
http://cristian.sulea.net/blog/disable-browser-caching-with-meta-html-tags/