Preached on money on Sunday. Here's the sermon - Matt 6:19-24 was the text.
Here are some other sermons on money that have helped me. Check them out, but be warned:
These sermons could seriously harm your wealth (i.e. your earthly treasure !)
Mark Prentice on Matt 6:19-24 (seriously awesome)
And once convicted - why not give to Gospel for Asia. I dare you to find a better kingdom investment!