sermonindex
Saints,
I want to recommend to you if you want to host your mp3 sermons freely and also get exposure for them on the internet to use http://www.sermon.net they have already 180,000+ sermons hosted. Simply go there and signup and start uploading your content. Even if you host your sermons at your church website or another place this is a great way to share the sermons with more people ie the traffic coming to sermon.net
Whether you have a blog, church site etc this is a great solution and they even let you have a embeddable flash player with all your sermons to post on your website.