Echofon comes from Naan Studio, the same company that makes a popular Firefox plugin for Twitter. Aside from its sleek interface, this app offers all the features you’ll ever need for casual tweeting. Replies, favorites, retweets and direct messages are all a breeze on Echofon, and a built-in browser makes it quick and easy to view links to external websites. In-line links to #tags and @mentions provide easy access to instant tag tracking and user timelines/profiles. When you open the app, it automatically scrolls to the first unread tweet in your timeline, and Echofon’s @replies include a link to see the whole conversation, so it’s easy to keep track of who said what in a chain of @replies/mentions. Echofon actually makes tweeting easier and more hassle-free than the official Twitter site — so much so that you might find yourself using your iPhone/iPod Touch as your primary Twitter device. The “Pro” version drops the free pricetag and adds more features, including support for multiple accounts, a landscape keyboard and user-authenticated bit.ly.