[theanonymousone]

My biggest scare in setting up a service where users can upload something, is the probability of "problematic" material. Is there any solution to this?

[boo-ga-ga]

Is it a problem your service doesn't provide sharing functionality? I.e. I can imagine illegal content can be a problem if you do an image sharing service. But if it's some utility, you don't store anything for long and that's it and forbid any illegal content in terms of use.

[tomjen3]

You need to not store it for more than a few minutes - otherwise people can use it as a host by sharing the account