Titanic.
Oh sorry, I got confused, you said "overlooked" not "over-watched".
Neil, Rushmore is the only movie I have ever purchased. Excellent! It's neat to see the two guys who run the cosmic cup (on oaklawn) restuaruant in all of the Anderson bro.s movies. One of them has a big role (as the Indian butler) in The Royal Tenenbaums.
The movie that comes to mind for me in the "overlooked" class, is "Besieged" starring Thandie Newton. I think Benardo Bertoluci directed. A lesson in saying alot with few words.
Not nearly as overlooked as Besieged, but far more than most mentioned here, is "The Big Kahuna". Kevin Spacey, Danny Devito and Peter Facinelli. Whatever movie got best picture and best actor that year (I think it was Gladiator or Titanic) stole it from a much better movie and performance. It also really makes a thinking witness think more, or at least it did me, with it's themes of spirituality and honesty. I think there is movie to be made along the same lines about witness issues.
This one will be overlooked till next week, when Halle Berry will win best Actress at the Academies, "Monsters Ball". See it and weep.