A friend of mine's Skype was "infected" with a bot that sends links to it's friends. The link points to LinkedIn, but as soon as you make a GET request, it redirects you to an advertising page. This is the link it sent:
https://linkedin.com/slink?code=er_a7nN#60097=user_im. Open it in virtual machine just in case.
What is strange about it, is that they use a foreign domain (namely linkedin.com), to trigger the redirect to the ad. How is this even possible? I tried inspecting HTTP response message to see what they did, but since the response has 301 status code, no entity body is being sent.