CMS detection
There are a few websites and tools that will tell you what CMS a website uses for development which can be a little quicker than scanning through code to find something to identify it.
The best tool I've found is an app on my iPad called CMS Detect, after using tools like this for a little while you'll get an eye for which script a site uses.
Keep in mind this tool is primarily just going to tell you if its wordpress, iis, drupal, joomla, ruby on rails, and whether or not the site uses google analytics. It will not tell you more obscure information like "LuckyShare.net using XFileSharingPro script" - although this would be interesting to have if it wasn't so damned easy to spot 90% of the file sharing hosts that use XFileSharingPro, lol