Arya/The Crew of the Titan's Daughter (Spoilers Extended)

Its amazing how you can find something new each time you read the series, but with each subsequent read those "new things" you find tend to be smaller and smaller (though usually no less interesting).

Here is something major/quite obvious that for some reason I missed every time I read (although it definitely has been pointed out by other users):

The crew of the Titan's Daughter wants Arya to remember their names so she can't kill them later

We know the ship didn't want to take her until she showed the coin:

Jaqen said to say the words too. Arya crossed her arms against her chest. "Valar morghulis," she said, as loud as if she'd known what it meant.

"Valar dohaeris," he replied, touching his brow with two fingers. "Of course you shall have a cabin." -ASOS, Arya XIII

And while due to the oddness of sailor's luck:

The crew of the Selaesori Qhoran had been pleased enough when he first came on board; a dwarf was good luck, after all. His head had been rubbed so often and so vigorously that it was a wonder he wasn't bald. But Penny had met with a more mixed reaction. She might be a dwarf, but she was also a woman, and women were bad luck aboard ship. For every man who tried to rub her head, there were three who muttered maledictions under their breath when she went by. -ADWD, Tyrion VIII

some of the crew shuns her, but due to them knowing who she is/what she is about to be others do the alternate:

The captain had given her passage but he had no time to speak with her. Some of the crew shunned her, but others gave her gifts—a silver fork, fingerless gloves, a floppy woolen hat patched with leather. One man showed her how to tie sailor's knots. Another poured her thimble cups of fire wine.

But later they make it a point of her learning their names:

The friendly ones would tap their chests, repeating their names over and over until Arya said them back, though none ever thought to ask her name. They called her Salty, since she'd come aboard at Saltpans, near the mouth of the Trident. It was as good a name as any, she supposed. -AFFC, Arya I

and:

"You know my name," said Yorko from the boat.

"Yorko Terys." -AFFC, Arya I

This was likely due to the fact that Faceless Men can't kill people that they know:

The priests used the language of Braavos, though once for several minutes three spoke heatedly in High Valyrian. The girl understood the words, mostly, but they spoke in soft voices, and she could not always hear. "I know this man," she did hear a priest with the face of a plague victim say. "I know this man," the fat fellow echoed, as she was pouring for him. But the handsome man said, "I will give this man the gift, I know him not." Later the squinter said the same thing, of someone else. -ADWD, The Ugly Little Girl

TLDR: The crew of the Titan's Daughter makes sure she knows their names so that Arya will be unable to kill them in the future if the Faceless Men are contracted to do so.