- what keywords a competitor is bidding on
- all the ad copy they are running
- who all the unigue competitors are for all those keywords
- what position the competitor is organically for relevant keywords.
You can also run the report on your own domain to see especially how rank organically and who the other competitors are bidding on the keywords you bid on.
It works for Google and Yahoo.
There is a Quick Report which gives you a brief overview but I suggest running a full report (which can take a couple of hours to run) but they will email you when it is done, as this will give you the best information.
Hope this helps your Internet Marketing efforts in a small way