We need applications (web-based or desktop-based) to automate the extraction of our data from one cloud and then upload it to another. Say, for example, you want to move from Facebook to MySpace. You log into your Facebook account and then run the programme (in another tab of the browser if web-based or from your computer if desk-top based). All your contacts, personal description, hobbies, messages, etc are downloaded and then uploaded to your new MySpace account. It could even automate a message to your Facebook contacts saying "I've gone to MySpace, please join me!". Obviously there is some tweaking to do as the MySpace set-up differs. But much less than starting afresh.
Other examples: downloading all your emails, labels and contacts from your Gmail account; downloading your music preferences from Spotify or Last.fm.
Are there legal restrictions to doing this? Companies could perhaps tap into the open-source community to avoid this. Even if not, the website suffering the automated access would seek the block the access to stop users leaver their service. The applications would need to be continually updated to circumvent the counter-measures.