Do graduate admissions follow links? Do graduate committees follow links, to personal websites, the applicant provides on his statement of purpose?

How common is this? If there are no visits one has to assume his application was not accepted / no one is taking a look?
For applications like the NSF Graduate Research Fellowship, candidates are explicitly told not to include such links, because it creates an unequal playing field, and that these websites might be used as an "end-around" against page and length restrictions. Similar rules might also hold for other applications as a result.

On the other hand, some schools may ask you for such a link, in which case there's a good chance it will be seen if someone is interested in you. But if you're not specifically asked to include such a link in your application, there's no guarantee that anyone will look at whatever's posted.