In the last few weeks I've used the approach to competitive analysis as explained in this UX Matters article, Differentiating Your Design: A Visual Approach to Competitive Reviews, by Michael Hawley.
We have been looking at imagery on the web to spot trends and see how others are effectively or ineffectively using it. This method is working wonderfully and really tells a great story about where we can differentiate our design from our competitors.
I love that the analysis isn't focused solely on usability, but emphasizes the factors you and your stakeholders think are important. The key is in getting the right dimensions or spectrums with which to measure.
Now that I've been through it once, it'll definitely be in my bag of tricks.