It may not be the absolute glossiest Twitter app for iPhone and iPod Touch, but the newly-renamed Echofon for iPhone is among the fastest and easiest to use. Your friends' timeline, the logical default screen, show new tweets in blue, for instant recognition. It's joined by screens to filter out tweets in which your own handle name is mentioned, your direct messages, and your favorites. There's also a search screen that can search for people and topics, can turn up trends--some of the popular topics at any given moment--and can also tap your geolocation to display public tweets from people nearby. You can even specify the mile radius.
The built-in browser keeps the Web pages of the links you follow within the app. You can view any user's profile, add new contacts and block them, and quickly send a reply or direct message in a response to a tweet. Tapping a single button makes retweeting easy as pie. Perhaps the most useful auto-fill timesaver is in the composition window, where you can tap one of three buttons to geotag your tweet, take or upload a photo, and select a Twitter buddy to reply to.
There are limitations, however. The browser is the only part of the app that supports landscape mode, you cannot delete direct messages, and push notification is reserved for the pro version.