I got waylaid at the Future of Web Apps conference today by the folks from Zapr. They make a free peer-to-peer file-sharing utility that's not just targeted at real people (as opposed to geeks; see AllPeers) but that I think they could actually use. Sharing a file or a directory does require a download, but unlike most other peer-to-peer sharing systems, receiving a shared file does not. It works through Web links: The application gives a shared asset a URL, which you can e-mail to your friends or post on the Web. People who go to the URL get a Web page served up by your PC, which then allows them access to the files you're sharing.
A big advantage of this concept is that once you share a directory, anything you put in that directory is easily accessible by anybody who has the link. And as long as the files are on your PC, they remain shareable. Free hosted sharing access to your files usually expires after a few days.
The major downside to Zapr is that you have to leave your computer on, although a future enhancement of the product will include paid, Web-based storage. Another big downer: No security, at least not in the current product. If the URL of a shared asset gets out onto the Web, anybody can download directly from your PC. Again, future releases will have security.
If you don't want to run an application to share large files, you might want to check out YouSendIt, which, like Zapr, allows receivers to get files by clicking on standard links. Since YouSendIt stores files on its own servers, you have to upload what you want to share, but then you don't have to leave your PC to allow people to pick it up. The hosted transfer model isn't as flexible as peer-to-peer sharing, but it is easier to use for both senders and receivers.