John recommended I try DropBox (as part of my never-ending quest for document-repository zen), and I love it so far. They get major points for detecting my browser and customizing the download page to Firefox (not Chrome though).
But let’s address the elephant in the room, it’s a big whopping (theoretical) security hole; I’ve just given a 3rd party read write access to my hard drive without looking at the source code (all programmers like to imagine that we’d read the source code if provided, just like all English Majors convince themselves that they’d really like to read Anna Karenina if only they had the time). DropBox stores a copy of all your files (2GBs worth) on their Amazon S3 account (I love that product too, this might become a series). I agree with Paul Stamatiou that it’d be really cool if I could just use my own S3 slice (not that you’d save much money, 50GB of space at S3 costs $7.50/month and they charge $10 plus give you versioning which takes up still more space — someone at Y Combinator has probably already noticed and built their own.