You can go to http://www.thebible1.net/audio/tullstar/ and download hundreds of lectureship audio files for free. Paul and Shirley Tuller have been recording lectures on both audio and video for many years. They have been converting all their files to .mp3 for free downloads.

Shameless plug for my podcast http://jwmcnieltx.podomatic.com/
(I havn't updated it for a while)

Oh, and while I'm at it - here's the one for Vidor church of Christ gospel meetings etc. http://vidorchurchofchrist.podomatic.com/