MP3s and Podcast Resources
As you may have guessed, the Internet has mp3 and podcast and audio resources too many to list here. Let me provide a few which I think may be very helpful to you.
One Place
There is a site which contains links to (seemingly) every well known Christian broadcast that exists. You can find it here . If you want to find programs such as John MacArthur's "Grace To You", R.C. Sproul's "Renewing Your Mind" or a classic such as J. Vernon McGee's "Thru the Bible", you can find them here. They are downloadable as mp3s and are typically free. Many of the ministry sites found at One Place offer an RSS feed by which you can automatically download their program.
White Horse Inn
While it can be found on One Place, this ministry deserves special mention. It is a weekly podcast in which ministers from four different Protestant backgrounds will discuss a theological topic on a level which everyone can understand. The link to the White Horse Inn podcasts can be found here.
Issues, Etc.
This is a daily radio program which archives its programs online. They can be downloaded as mp3s. The host, Todd Wilken, is a minister in the Lutheran Church Missouri Synod. The programs cover a tremendous amount of topics. Sometimes, it is a Christian perspective on some recent world or national event. At other times, the topics will cover church history or theology. Like the White Horse Inn, the discussion is intelligent, insightful and geared for a popular audience. The link to Issues, Etc. on-demand mp3s can be found here.
Sermon Audio
This site probably contains more mp3 sermons than any other on Earth. As of this posting, there were over 267,000 audio sermons available. There are a number of current preachers whose sermons are on this site. There are also a number of sermons from pastors who have since died and whose sermons mean just as much today as when they preached them years ago (A. W. Tozer and Leonard Ravenhill are good examples). The link to Sermon Audio can be found here.
Troy Christian Chapel Sermons
Don't forget that TCC has a webpage with mp3s of sermons which have been preached at church. The sermons of Dan Lewis, Jon Enright, Jake Stirnemann, Chad Lewis and Brian Torres can be found here. There is also the option to download the sermon through a RSS feed. This is a great way to catch up on a sermon you may have missed while being out of town on vacation or a camping trip.
Theology Network
Theology Network is based in the United Kingdom and has a tremendous number of resources to grow in the faith. Their site contains numerous articles, electronic copies of entire books (such as "The Bruised Reed" by Richard Sibbes) as well as an abundance of teaching mp3 on a variety of topics. I've listened to tens of hours of the teaching mp3s from Theology Network and they cover a variety of subjects quite well and in a very easy to listen to style of presentation. Their link can be found here.