Hot answers tagged communication
Disqus is one of the solutions.
I use Dropbox. It's excellent.
Google Sidewiki does what you're looking for, but only other Sidewiki users will see your comments.
PBWorks is not bad. I've heard a few ppl use Wikidot as well. PBWorks Wikidot
Chrome Extension Cloud Save facilitates this to some degree. (Review) It's limited to services with an API (Dropbox, Google Docs, box.net, plus several more) but I expect more to be added. I've been using it on my Cr-48 and it has made that device infinitely more useful.
I like Skydrive at http://skydrive.live.com it has 25GB, Office docs can be viewed and edited online, photos can be presented in slideshow, and folders with many files can be downloaded at once in one zip file. Also, you can have folders shared privately with as many people you like, delimitted by the email. All you need is a WindowsLiveID, wich you have if ...
Yahoo! Groups seems like it would fit your requirements.
Dropbox as mentioned is great for file sharing. For other communication and project management, we're using Comindwork. It has some basic file sharing as well.
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