I'm working on extracting the sentiment from YouTube comments, blogs, news content, Facebook wall posts, and Twitter feeds. I'm looking for an automated way to do this: the two third-party solutions I've found have been AlchemyAPI and RapidMiner. Are these the best way to approach this project, or should I be using something else? Is there a more efficient way to approach sentiment analysis? What techniques have worked for you in a project like this?