Create a smart playlist (the simplest way is to hold down the 'Option' key and click on the little gear at the bottom far left of the screen; you can also go under 'File' to 'New Smart Playlist' and use the following settings (or variations on them):
Depending on how much music you have, you may want to set the minimum playcount higher or lower, and 1 gigabyte may be too large or too small.
[√] Match [all] of the following rules:
[√] Limit to [1 GB] selected by [least recently played]
- [Play Count] [is greater than]: 6
- [Last Skipped] [is not in the last] 1 months
The purpose of this playlist is to collect music that you used to listen to a lot, but that you haven't listened to recently. (The bit about 'play count' captures the first part, and the 'least recently played' the second.) One problem I've had with this sort of playlist is that if I'm using it to populate 'Party Shuffle', for instance, and a song pops up that I don't feel like listening to now, then even if I skip over it it may pop up again after a little while. The 'Last Skipped' bit means that once I skip over a song it won't reappear in the playlist for another month, which is quite welcome. (That's the new iTunes feature I mentioned.)I hope someone finds this useful!