Here's a good video essay - blogger Kevin Lee and critic Matt Zoller Seitz (formerly of the New York Times and New York Press), on Eternal Sunshine. Nothing earth-shakingly profound, but worth a look. Lee himself says he wishes he'd had more time to prepare.

Zoller Seitz observes:

I think it speaks to the way we try to keep people alive by remembering them. As long as he can remember her, as long as he can preserve some memory of her, then she is always going to be real, and she's always going to be present.

In 2006, Seitz's wife abruptly passed away, aged 35. Says Tram (who sent in the link), "It's a nice reminder that good films offer more than just cheap thrills."