It is very important to make sure that all posts to the forum are answered in a timely manner. This is especially nice because it lets people offer support or celebrate with the person making the request. I fyou have any experience with this, please let me know. There are many ways to go about this, but the single most common one seems to be using a 5 part series author of which I have not been able to track down. There are many resources for doing online evangelism in the resources section of this site.
Text is the usual format, but there are some sites using streaming audio now.
Real Audio seems to be the most common format. In addition to the current sermon, previous sermons are also available. I would be interest in hearing of any churches that do this in conjunction with shut-in ministries. This is usually done by relating the church to the community in which it is located. Better sites generally offer more information about each event.