I think it would be great if you could link tracks in your library to other tracks. A nested menu like the fx or flip menu would make sense and look great UI wise.
It could be used for many work flows.

A couple of examples that come to mind:
1: You could link every remix or clean edit of a song to that main track you might play.
2: You could link songs you know mix well with the selected song. (Typically I write these under the "comments" metadata tag)

--------------------------------[off] [SYNC] [LINKS] <--------- Example the linked tracks button
--------------------------------_________________________
[ ]--Cue 1--]--[ ]--Cue 5--] | |
[ ]--Cue 2--]--[ ]--Cue 6--] | |
[ ]--Cue 3--]--[ ]--Cue 7--] | |
[ ]--Cue 4--]--[ ]--Cue 8 --] | |
[ ]---------LOOPS----------] | |
[ ]---------LOOPS----------] | |
--------------------------------| |
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