Some of these services have their own ability to backup your data to your PC. Google Docs has been very good about that with their one-click ability to download all your documents in one ZIP file. Through their Data Liberation Front they have been very good about letting you have your data.
For those few that let you download your own data, it is only as reliable as your discipline of actually backing up your data. For me, my intentions are better then my actions in that respect. And for those that do not offer you your own data, you are just out of luck.
A new service will backup many of your Cloud Apps data for you, on regular intervals. Many of our Apps have an API (a programming interface) available to developers. This service uses the various API's to copy your data for you.
Backupify backups data a growing variety of services. Currently they claim :
- Google Docs
The great news is if you sign-up with Backupify before January 31, 2010 the service will be free to you.
I've used this for a few weeks, and it says that it is backing up my data successfully. I have looked at a few of the files, and some of my backed up Flickr photos. I have not done done the ultimate test; have a system fail and recovered my lost data from a Backupify backup. I have to go on a certain amount of faith it will work when needed.
There is also a trust issue. You have to give Backupify your login credentials for each service.
Overall, the peace of mind of having my data backed up exceeds my anxiety about others having my credentials.