Almost every character in Amélie collects something, and we're not talking about your usual stamps, coins, or Pokémon cards here.
Nino collects footprints and photo booth photos. Amélie picks up skipping stones everywhere she goes, whether she's visiting Collignon's parents or going on a nighttime gnome-napping mission at her father's house. Joseph maintains a time-stamped record on his voice recorder of what all the women in the café say or do. Madeleine, the sad landlady, keeps a sheaf of letters from her husband's days in Army Camp. Gina collects proverbs; Georgette collects ailments.
Everyone collects something, and often for different reasons. Sometimes it's to preserve something that would otherwise disappear forever, and sometimes it's because the person can't bear to let go, and sometimes it's a little bit of both. Either way, none of the characters is really living a full life; they're only collecting the bits and pieces of life they can get their hands on. It isn't until Amélie shakes things up that these people wake up and start living again.