And when you see the boxed clusters on the screen (nicely done, by the way),

Thanks. As with all good software features, I put this is because I was missing it. I’d already coded the “find the most clustered album” code and realized I was having trouble identifying the clusters.

And I wonder if the wording in the program should be called "cluster" instead of "comb" but that's not important really.

I can change it to whatever you like.

It seems to consider any group of songs that is more than two to be a cluster.

Correct. I thought about flagging “two-fers”, but decided against it.

What's the distance-between-songs criteria?

Ten songs max, though I could make this settable if you wanted. This seemed like a good number because it's shorter than most album lengths, so I'd think it'd really stand out.