TweetMic lets you record audio clips on your iPhone and post them to Twitter. It has an intuitive interface that makes posting audio files on Twitter completely painless. TweetMic Pro has multiple twitter account support.
UPDATE: Tweetie is now the Official Twitter App for iPhone, simply called Twitter
The app so nice he made it Twice! Tweetie 2 is an award-winning Twitter app for the iPhone and iPod Touch, stowing away an unbelievable number of features into a simple, easy, attractive interface. Seriously!! Every pixel of this interface is precisely designed and intuitive to use.
Readtwit is a web service that finds links in your Twitter stream and formats them as an RSS feed. You may be saying "hold on here, I can get an RSS feed of my tweets from Twitter.com" but Readtwit has some goodies that make it a worthwhile service.
First of all, it only loads tweets with links in them. Tweets with no links will get skipped, so if you're not a fan of chatty banter, this will appeal to you.
Echofon for iPhone, formerly TwitterFon, is a super-fast, easy-to-use Twitter app sporting video recording. They changed their name presumably to remove the whole word Twitter out of the app name to avoid trademark trouble. Although the free version is definitely stripped down compared to their $4.99 Pro version, Echofon for iPhone has quite a few features:
TwitBird Pro is a full-featured iPhone Twitter app that supports landscape view for tweets and the inline web browser. As they claim in the App Store description, landscape view is available on pretty much every screen of this iPhone app. If you are a fan of typing or web browsing with a wide screen on the iPhone, this is the twitter app for you!
pic.im is an image uploading service offering integration with tr.im and Nambu. All three are part of the Nambu Network, and as a result play nice together.
You can download the pic.im app to upload pictures on your iPhone. You can just as easily share images from your desktop using Nambu. Both show you some basic statistics about the photos in your pic.im account.
Twalala is a simple web application with some stream filtering so you can control what you see, and what you don't want to see. If their name confuses you, think of a kid sticking his fingers in his ears and saying "lalala!" to block out what someone else is saying. From their website:
Get ready to take control of your twitterstream. twalala is a client for Twitter that allows you to control what you see, and more importantly, what you don't see in your twitterstream...
Finally, Twitter with a mute button.
Tweetings Mobile is a secure, full-featured Twitter app for iPhone and iPod Touch that supports Push Notifications. Although the development company appears to make primarily Windows software, their venture into the iPhone space is very commendable. Tweetings Mobile can do everything Twitter.com allows you to do, including posting tweets, following/unfollowing/blocking users, reading @ mentions and DMs, and public timeline searching. Some notable features:
Twitterrific for iPhone is a fantastic, feature-packed iPhone twitter app for beginning and advanced users alike. First of all, their 2.0 release saw a major performance and feature overhaul compared to the original version, which was a great twitter app to begin with. This interface is amazing! It's quick and responsive, and scrolling past a hundred tweets with one flick is no problem. But it's not just looks, because there is a LOT packed under the hood:
Logpost seems to be your run of the mill web-based Twitter client. It offers no killer features, and being a web app, offers no speed or ease of use that users expect out of a native application for their mobile devices.
The interface is designed to be familiar on an iPhone or iPod Touch, although their home page claims compatibility with devices from Apple, Android, Palm, Blackberry, and Windows Mobile. For this review, Logpost was tested on an iPhone.