I’d like to collect data from internet groups (e.g., message-boards, weblogs, etc). Aren such data “publicly available” and, thus, do I need to bother with seeking ethical approval for the project?
Yes, you need to seek ethical approval for projects involving material found on the internet. It is important that you carefully read the BPS document about conducting research on the internet before preparing your application. As you will see on pp. 3-4, the distinction between “public” and “private” space is blurred in this context.