Might not be a good idea, but I wish to encrypt all the data in all columns in SQL database. Quick search gives that php doctrine simply can't do that, sqlalchemy and django-extensions can. It surely would be much harder to manipulate information, but at least user data would be much more safe that way.

Also I think would be nice to let users to save all the data offline, to give them a choice to not to store data in your database of your web-service. But again, it is extra work.