A new open source one
... I've tested it with a few batches and seems to work pretty darn well, unfortunately it does not feature a "compatible" tracks area.
But bear in mind that key detection is an estimation process like BPM detection. It may be wrong in numerous cases!
Just like BPM or Sync etc ... trust yer ears, you'd double check in your headphones first anyhow, it would be a VERY nifty feature.