The fluxkraft project is just starting, but there are already integrations for the most important web services including Twitter, Facebook, flickr, Dropbox and Linkedin. See the full list on https://drupal.org/project/fluxservice.
Note: When there is an integration module available it doesn't mean that every API feature is supported. In case you are missing something write a feature request or try to contribute it yourself!
Do you know another web service that should be integrated immediately? Write a comment and tell us what usecase you have in mind.