With the news that the social bookmarking site Ma.gnolia might have gone down for good, it's a good time to consider exactly how we can ensure we don't lose all the data that we collect in various online services.
Feed Readers make it easy to do this. I can download an OPML file from Bloglines, either to backup the list of feeds that I subscribe to, or to read them in another service like Google Reader. OPML is used as standard, in feed readers and podcast aggregators.
The same is possible with some social bookmarking sites, but there doesn't seem to be a standard way of migrating bookmarks similar to OPML. I use Delicious, and this allows me to download a list of my bookmarks, along with data like my tags. However to import them in to Google Bookmarks I'd need to run them through a third-party program rather than an official Import Bookmarks function.
At the far end of the scale are virtual worlds. There are moves towards your avatar being able to move between worlds, but this is in a very early stage. The fact that Google closed Lively while educators were using it, shows that it is important to be able to move your avatars and creations, in some form, to another environment.
Anyway, the point of this post is really to emphasise the importance of backing up your data. If you've found some web services that you are settled with, and that you are collecting large amounts of valuable data in, the experience of Ma.gnolia shows us that it's not as safe as it sometimes feels.