Facebook recently launched a handy feature that lets you export almost all of your Facebook data into a handy ZIP file. All you have to do is visit Facebook's export tool and click the download button. Then you'll get an e-mail when your file is ready to download to your desktop. This is an ideal task to do once a month or even once every season. You don't want to lose all those mobile uploads should the worst happen, and it makes it much easier to move your data around should you wish to leave Facebook one day.
The best way to save all the hard work you put into your blog posts is to save them on your hard drive before posting them to the cloud. Many blog writing programs are compatible with the most popular blogging platforms such as Blogger, Wordpress, or Tumblr. Mac users can use a blog writing program such as MarsEdit ($39.95), which saves a back-up of every blog post you write using the app. For Windows users, Microsoft's free Windows Live Writer will save your posts written using the program to a file in your Documents folder called "My Weblog Posts." Most blog services also have an export feature to download all the posts you've already written.
You could subscribe to your own Twitter feed using a desktop RSS reader such as NetNewsWire for Mac or FeedDemon for Windows. But most desktop programs limit how many items you can download via RSS. Another option is to try a free service such as TweetBackup and Tweet Scan Backup, which let you grab your past tweets and export them to your desktop. Keep in mind these services can only grab a chunk of your most recent tweets (Tweet Scan Backup only grabs 1000). If you tweet more than that or are coming close to that limit, make sure you back it up before all your 140-character witticisms are inaccessible.
Backing-up your data may be a pain, but if you want to maintain control while still enjoying Web-based services you owe it to yourself to back up your stuff locally.