If you absolutely need server stuff, Tahoe-LAFS [0] looks good. The mailing list is great[1-2]. An interesting service uses it, Least Authority[3] offers Tahoe-LAFS-on-S3[4]. It runs for free on Dropbox, too[5].
"Tahoe-LAFS is a Free and Open cloud storage system. It distributes your data across multiple servers. Even if some of the servers fail or are taken over by an attacker, the entire filesystem continues to function correctly, including preservation of your privacy and security."[0]
TL,DR: Storage nodes can't decrypt your data, so you don't have to trust them.
I would not feel good about my data on random people's servers. I don't trust the encryption. not today and definitely not 10 or 30 years from now when they could still have the data.
That's why its being open source is relevant. Paranoid folks like us set up a private network locally or on any number of our own physically secure servers.
It's also an interesting question:
How comfortable do we feel relying upon the "principle of least authority" long-term in a mixed-trust environment? i.e., a p2p-style Tahoe-LAFS grid, or deploying it privately using a commercial vendor like Amazon S3 (either directly or through Dropbox for free), on our own servers, and everything in between.
You might not trust companies from certain countries with your data, and you shouldn't be forced to in order to store it* in the cloud*.
"[…] You might not trust Companies with your data either, and you shouldn't be forced to in order to store it in the cloud". That is exactly our goal: we don't like to be forced to trust companies for the security of data, so we are developing a service where users actually don't have to trust even us… although some trust in the encryption algorithms used will be required, given that you can see the implementation of course.
"Tahoe-LAFS is a Free and Open cloud storage system. It distributes your data across multiple servers. Even if some of the servers fail or are taken over by an attacker, the entire filesystem continues to function correctly, including preservation of your privacy and security."[0]
TL,DR: Storage nodes can't decrypt your data, so you don't have to trust them.
[0] https://tahoe-lafs.org/trac/tahoe-lafs
[1] https://tahoe-lafs.org/cgi-bin/mailman/listinfo/tahoe-dev
[2] https://tahoe-lafs.org/pipermail/tahoe-dev/2012-December/thr...
[3] https://leastauthority.com/
[4] https://leastauthority.com/howtoconfigure/
[5] https://tahoe-lafs.org/~marlowe/TWN27.html (mid-page)
(no affil.)