When I think internet I think panopticon; however, instead of there being a single point of view from which all parts are visible there are multiple.
It is this multi-angled view, a characteristic of the internet, that impacts the way in which researchers deal with human subjects.
What is private or public behaviour?
When can/does covert observation take place?
The "common rule" a federal regulation involved with "the protection of human subjects" proves to serve as the primary source of problematic issues related to internet research. It is as such because of the inherent ambiguity in definition of the public and the private on the internet.
The blurred boundaries of that which is private and that which is public affect the process of informed consent, the assesment of risks involved, and the protocol a research project must establish in protecting the privacy of an individual with regards to their rights to personal privacy and the confidentiality of the data which they provide.
In essence, the basic ethical principles, as described in the "Belmont Report", come into question when utilizing the internet, especially with regards to "respect for persons" and "beneficence" as described in the aforementioned. It is as such simply because the internet was not accounted for during the development of the Belmont document.