Here’s a source for some quick, helpful competitive research – much of it free: Spyfu.
Enter any URL and here are some of the things you’ll see:
• URLs of top competitors, both for organic search and paid search
• Estimated daily traffic from organic search and paid search
• Estimated daily ad budget range for paid search
• Estimated paid search budget by month for the last three years
• Top ten paid keywords
A limited number of results for each category is delivered for free. Complete data requires a subscription. Monthly and yearly plans are available. Results seem impressively accurate. Just using the free feature can provide some helpful information, whether or not you run paid search campaigns … check it out!