Photo sharing website for wedding photo collaboration

Hi,

We recently had our wedding and we now want to setup a photo album where people can upload their photos of the day.

I tried using Google's Picasa and enabled the collaborate feature but very few of our guests have google accounts and so I need something that is dead simple preferably something that doesn't require any user registration.

Do you know of a website that does this or something I can install on my server (linux/php)... Any suggestions welcome

Thanks

Kenneth