Funny enough I've worked on this for a while and while it's a good idea the effort required is somewhat less than using existing application GUI's to enter data and extract data via feeds or API's. The idea I tried was creating an interface to update multiple services (twitter, flickr, delicious ...) via one page, send to a database and use the api's to auto-update. The hard bits ...

- how do you add more services easily?

- how will your display code handle lots of empty fields? Lots of conditionals in your templates. Is your templating engine up to it?

- how do you selectively and easily send data to one application but not another, some times? Can you change for instance sending links to flickr but not to delicious on a one time basis?

- how do you handle sites that have no API's or feeds? Like hackernews which had neither for a long time.

The one key advantage of this method is you capture data before you propagate it. So if your well thought out 100 word post (with references) dies because your browser crashes or you press the back button you have a local copy.