I'm sure there are a lot of people who haven't seen Amelie (or originally known as Le Fabuleux Destin d'AmĂ©lie Poulain), but I wouldn't exactly call it overlooked. If anything, it was a relatively huge hit. I mean, 5 Oscar nominations, 7 Bafta nominations, millions at the box office world wide. Granted, it wasn't a blockbuster, but it's not an obscure little arthouse movie either.
I would rather nominate Jeanet's older movies (no, not Alien: Resurrection), the ones he created with Caro, namely Delicatessen and La CitĂ© Des Enfants Perdus (City Of Lost Children) as overlooked films.