1. The CSS attributes IE supports, including versioning:
http://msdn2.microsoft.com/en-us/library/ms531207.aspx

2. Dynamic properties using 'expression' to execute javascript
http://msdn2.microsoft.com/en-us/library/ms537634.aspx#Implement

This is a simple example of executing script through an expression property, the backslashes are just escaping mechanisms allowed in the CSS spec.

.thisworks

    {visibility:hidden;

    margin:expre\ssion\(alert\(\'\'\)\);

    }

3. Conditional comments available in IE, notice how in this example the legacy style was non-standard.
http://msdn2.microsoft.com/en-us/library/ms537512.aspx

Example:

<!--[if !IE 6]>
<p>IE7 or IE5 only</p>
<![endif]-->

Specifying the User-Agent for enabling document compatibility:
http://msdn2.microsoft.com/en-us/library/cc288325(VS.85).aspx

<meta http-equiv="X-UA-Compatible" content="IE=4"> <!-- IE5 mode -->
<meta http-equiv="X-UA-Compatible" content="IE=7.5"> <!-- IE7 mode -->
<meta http-equiv="X-UA-Compatible" content="IE=100"> <!-- IE8 mode -->
<meta http-equiv="X-UA-Compatible" content="IE=a"> <!-- IE5 mode -->
<meta http-equiv="X-UA-Compatible" content="IE=edge"> <!-- IE8 chooses highest version-->