Monitor Who's Viewed Your Profile
On the right side of your homepage, look for a box called "Who's Viewed My Profile." Click that link to see a statistics page that shows who has viewed your profile in the last week, such as "Someone at XYZ company" or "Someone in the Greater Boston Area." You'll only view more-detailed descriptions if you are a paid LinkedIn member.
If you don't want others to see that you've viewed their LinkedIn pages, be sure to change the corresponding privacy setting.