subscription

Twitter Mulls Subscription Product – what would make you signup?

From: Twitter Mulls Subscription Product, Tipping For Generating Revenue:

To explore potential options outside ad sales, a number of Twitter teams are researching subscription offerings ….. Other possible ways to generate recurring revenue include charging for the use of services like Tweetdeck or advanced user features like “undo send” or profile-customization options.

I was a big fan of Tweetdeck in the day, now I happily subscribe to Tweetbot on iOS / Mac, do you pay for your Twitter client, or would you consider it? If so what would be the reall killer feature to make you sign up?