You have to put attention in these iPhone applications about productivity and social relations. I love them.

Twitterrific

Twitterrific is the iPhone’s premiere app for reading and posting to the Twitter social network. The software has been designed to provide ease of use and a wide range of features while sporting one of the most elegant user interfaces available.

To get started, sign up for a free account at Twitter.com, then visit the App Store to download Twitterrific for the iPhone and iPod touch. You’ll be tweeting in no time!

Evernote

Evernote for iPhone lets you create notes, snap photos, and record voice memos that you can then access any time — from your iPhone, computer, or the web.

• Create text, snapshot, and voice notes any time;
• Snap photos of white board, business cards, or wine labels and Evernote will recognize the text in the images;
• Turn your iPhone on its side to scroll through an endless stream of notes;
• Quickly find your by location using Evernote’s map view.

Fring

fring is now available on the App Store making it easy for anyone to use fring on the original iPhone, iPhone 3G & the brand-new iPhone 3GS or iPod touch.
All you need to do is download fring on the App Store and within minutes you can make free calls with other fringsters™ or via fring using Skype, Skype-out or any SIP providers you choose.
You will have one searchable contact list with all your instant messaging buddies from Skype®, MSN® Messenger, GoogleTalk™, ICQ, Twitter, Yahoo!™ and AIM® so you can easily see who is available and where they can be reached before dialing or starting a live chat session.
In short, you can finally interact with all your favorite internet applications, services and communities from your iPhone.

Instapaper

Read saved web pages on the go, even offline, with Instapaper.

imply install the Instapaper app and download your unread articles when you have WiFi, EDGE, or 3G coverage, then you can read them anytime: on the train, on the bus, on line at the bank, or in space (you never know).

Like the Instapaper web interface’s Text option, the app downloads a text-only version of each page by default, using ideal formatting for maximum readability in either orientation on the iPhone and iPod touch.

Text-only mode also removes the need to zoom or horizontally pan like you so frequently need to do in Mobile Safari. And no more accidental side-scrolling when reading a long text column.

WordPress

Introducing the only iPhone app that lets you write posts, upload photos, edit pages, and manage comments on your blog from your iPhone or iPod Touch. With support for both WordPress.com and self-hosted WordPress (2.7 or higher), users of all experience levels can get going in seconds.