Widget+ is a free
file storage service,
supporting
widgets with filesystem access
and persistent
data, allowing them to
combine into more
complex web applications.
Therefor, this has become an instant
no-cost option for web applications
which can be deployed anywhere, on any website or blog.
The signup procedure is instant, there's no confirmation email to bother about.
Once logged in, you can start uploading files and build you apps.
You will be able to sign up users for your apps and instantly have different accounts for different users.