Yes, you can use as many general-purpose 3rd-party Web services as you want. The data from these Web services does not count against your 10k limit. However, cheating is not allowed. For example, entrants are not allowed to upload all project-specific design assets to Flickr and then reference them from the app to bypass the size limitation, or host project-specific code files in a Web service to bypass size restrictions. If your scenario is even slightly questionable, please contact us with the details.