We can show various interesting reports based on your last.fm profile.
We find all your "old favorite" artists based on your Last.fm overall, annual, and 6-monthly charts. We then remove any that are listed on your 3 month chart, weekly chart, or recent scrobbles.
What remains are your favorite artists which have not been played recently. Maybe it is time to pull that CD out from the bottom of the pile. Or maybe you can laugh at how your taste has changed.