Twitter isn't growing as quickly as it used to, so it can't just count on a horde of new social networkers to pump up its bank account. What's it going to do, then? Sell ads elsewhere, apparently. Sources for the Wall Street Journal claim that Twitter is planning to offer ads for the tweet feeds you see in other companies' apps and websites, sharing the money it makes with its partners. It's not certain who's onboard with the idea. Twitter reportedly cited both ESPN and Flipboard as examples during a presentation at CES, but a WSJ tipster says that there's no official deal with ESPN just yet.There's also no comment from Twitter so far. However, the strategy would effectively make it a very targeted ad network that makes cash whenever a company wants to capture the social zeitgeist, such as reactions to live events. It wouldn't have to worry so much about getting new users, since it'd make money even if you're simply visiting a news site that happens to have a live Twitter stream. And before you ask, there aren't any signs that these ads would pop up in third-party Twitter clients like Tweetbot -- from all indications, this would be strictly for content providers that want to make a little money on the side.