Echofon is a popular Firefox extension and OSX application, and this iPhone version will sync with both of them, while offering the same functionality and good design.
The free version is still packed with features. You can have multiple accounts, tweet photos or videos, link to a bit.ly account so you can follow your stats, choose your image service and more.
The main twitter feed works as you would expect, with links and profiles opening quickly. The limitation with this version is that Push Notifications will only work with messages from other Echofon users - your regular twitter notifications won't appear unless Echofon is open. This free version also features one advertisements at the top of your Twitter feed.
There is a search tool, that allows you to search Twitter, check trending topics and even see nearby tweets: Linked with Google Maps and your location, you'll be able to see who's tweeting what in your area!
For users of Echofon in the Mac or in Firefox, one of the best features of Echofon for iPhone is that it syncs with the other versions you use - this means if you get home and turn on your computer, Echofon won't still be notifying you of all the day's tweets.
While the lack of global Push Notifications is annoying, Echofon is otherwise a great, solid Twitter app that should be the number one choice if you use its sister apps on the Mac or Firefox.
Download and use it now: Echofon 5.2 free download