I wrote a couple of posts recently that might be of interest to Web developers. The first was on canonical URLs and the second was on the Fileinfo extension for PHP.

Google, Yahoo and Microsoft now support a new value for the rel attribute of the link tag that allows one to publicly specify their preferred version of a URL. The value is "canonical" and it's simple to use: <link rel="canonical" href="http://your-site.com/preferred/url/" />. Read my post

The PHP Fileinfo extension is useful for determining the MIME types of files. The returned type is not based on a file's extension, but rather on certain byte sequences at specific positions within the file.

The first post I wrote describes how to compile and install Fileinfo on a Media Temple dedicated virtual server. The second talks about how to use Fileinfo and includes a wrapper class that might be helpful.