from a recent post by AJ Tarachanowicz
I know Eclipse IDE  detects and allows you to set file encoding along with an HTML Tidy ability, CVS Clients, SSH Client, DB Client, Visual Diff (CVS vs Current History, Local History, Another Project, Different CVS), and the standard IDE feature.
With the release of Eclipse 3.0 it has definitely come a long way from 2.x. There are also serveral plugins avaliable for CSS, (X)HTML, php, phpDocumentor  struts, perl, an abundant amount of java plugins, UML, and much much more . It’s open source and it receives major support from major industry leaders such as IBM, Borlan, QNX Software Systems, Red Hat, SuSe, and Oracle just to name a few .
 http://www.eclipse.org – Eclipse IDE
 http://www.phpeclipse.de – PhpEclipse
 http://www.xored.com/download.php – TruStudio IDE
 http://www.eclipse.org/tools/index.html – Eclipse Tools
 http://www.eclipse.org/community/plugins.html – Eclipse Plugins
 http://www.eclipse.org/org/index.html – History of Eclipse