TweetDeck is totally free and perfect for those who need to manage multiple accounts, follow specific hashtags, reply to lots of other users and see exactly what's being tweeted in real time. You can organize everything you need in separate columns so you can see all of it on one screen. Keep in mind that TweetDeck is meant for the desktop web only.
TipTop Search is a Twitter-based search engine that helps you discover the best and most current advice, opinions, answers for any search, and also real people to directly engage and share experiences with. A search on any topic reveals people’s emotions and experiences about it, as well as other concepts that they are discussing in connection with the original search.