All Souls Church, Langham Place has an online archive of sermons dating all the way back to 1966!
All Souls is where John R. W. Stott was rector for many years. Stott is arguably one of the most influential and articulate preachers of the twentieth century. I've benefited from his expositional commentaries for years now, and have never heard him preach (until now . . . I'm listening to his sermon on Romans 3:21-31 as I blog). Wow. This is a gold mine! Did I say I was excited about this?
I hope you will check it out. You will have to register to use the site, but the sermon downloads are free. Check out the very helpful search features. As I said above, the sermons date all the way back to 1966 with John Stott's series on Galatians called Only One Gospel. Plus there are sermons by dozens of other preachers and teachers, including men like Don Carson, Mark Dever, Dallas Willard, Christopher Wright, and Philip Yancey. I'm serious - this is an incredible site. Check it out.