I was giving a demo the other day and that showed ReSharper's cyclomatic complexity plugin. It puts a squiggly underneath method declarations that have a cyclomatic complexity over 15, and also tells you what the cyclomatic complexity is:
It's a nice little plugin that lets me have some visual cues on methods that need refactoring. Of course, looking at the method body itself provides a good clue also. You can find this plugin, along with a few others, here:
Yet another reason to love ReSharper.