The CSS2 Opacity property doesn’t work in the current versions of Internet Explorer - through IE8. However, it has provided a way to achieve similar results with a different method, using IE’s filter property. Javascript frameworks usually work this in for you when you try to set an elements…

Blue prints for designers
IE NetRenderer

IE NetRenderer allows you to check how a website is rendered by Internet Explorer 7, 6 or 5.5, as seen from a high speed datacenter located in Germany. Just type in a URL in the field above and try it out - it’s free!

http://ipinfo.info/netrenderer/index.php

IE6 upgrade warning
Maximum picture height in newsletter - 1728px
HTML5 and jquery