Student logs into course website.
Student gets to a web page.
Reads a question or asked to comment on something. Student clicks a link or a record button on the web page. The instructor could then access the recorded file to hear the student's response and listen to the inflection in the student's voice. Ideally I would like this to be done via a web browser as well. I've heard of instuctors calling a server via the telephone and recording a lecture that is later posted, but I've not been able to find anything that's done through a web browser.