I think Filosync (www.filosync.com, currently in beta, I'm the founder) would work for this. You could have many projects in your cloud and only sync the one(s) you need to a given computer. We'd just need to add a feature that stores "previews" of the items in the folder so you could browse without downloading. But it uses S3 in your AWS account, so would be cost-prohibitive for a consumer storing terabytes.