Apple has over 500,000 applications written for the iPhone with over 2 billion downloads as of November.

Applications for IT administrators, road warriors, seekers of cheap gas, game players, etc are being downloaded at an unprecedented rate.

20 best picks for iPhone applications for 2009 (not necessarily in order):

Skype
Cost: Free
VOIP specialist Skype’s iPhone app was downloaded over a million times in its first two days of release, not surprising when you consider that it allows users to make free Skype-to-Skype calls on their iPhone from any Wi-Fi hot spot.

• NYTimes
  Cost: Free
  This app allows access to news from The New York Times. It also includes a customizable tool bar with instant access to finance-world updates. Articles and photos can also be made available offline.
• Amazon Mobile
  Cost: Free
  Those too busy to sit in front of their PC and shop can use the Amazon Mobile App, which features Amazon.com’s product listings. In addition to letting users compare prices, read reviews and make purchases, the app will store user-snapped photos of products on both the Amazon Mobile App and Amazon.com, through a feature called Amazon Remember.
• Bump
  Cost: Free
  Bump lets iPhone users physically bump their devices together and, in less than 10 seconds via the iPhone’s Internet connection, exchange contact information. Bump achieved notoriety as being the app downloaded by 13-year-old Connor Mulcahey of Weston, Conn., to win Apple’s billion-app countdown contest.
• Facebook
  Cost: Free
  The Facebook application lets the user keep up-to-date with his or her account on the social networking site, including the ability to upload photos while mobile.
• Google Mobile
  Cost: Free
  Google Mobile has deepened its functionality with new versions that incorporate voice search for the Web, the ability to Search with My Location, and access to Gmail, Reader and other applications.
• Google Earth
  Cost: Free
  The iPhone version of the popular Google App allows for tilting the iPhone to see mountain terrain, as well as the ability to search for cities and other features with Google Local Search, a variety of languages, and access to geolocated Wikipedia articles.
• Kindle for iPhone
  Cost: Free
  Soon after the debut of the Kindle 2, the next generation of Amazon.com’s e-reader device, Kindle for iPhone also rolled out, letting users download and read Kindle books, adjust text size and add bookmarks.
• Network Admin
  Cost: $5.99
  This app keeps a record of all clients’ network configurations, and allows those records to be shared with technicians and managers (the information itself is protected by 128-bit AES encryption using a private key and is accessible with the entering of a four-digit PIN number). Users can create custom categories for organizing information. The application requires an Internet connection, but data is also cached for 12 hours in the event that no such connection exists at a work site.
• WinAdmin
  Cost: $11.99
  A Microsoft Windows RDP (remote desktop protocol) client for iPhone and iPod Touch, which lets administrators have access to and manage systems remotely. Supports Windows 2000 Server, XP Professional, Vista (Business, Enterprise and Ultimate Editions) and Windows Server 2008 (Terminal Services Gateway is not supported), and has the capability to configure and save settings on a per-server basis.
• Pandora Radio
  Cost: Free
  Pandora is the iPhone version of the popular music-streaming Website. Users can log in to listen to their customized stations.
• Bloomberg Mobile
  Cost: Free
  This app delivers news, stock quotes, analysis, price charts and company descriptions-basically, much of the same functionality available to Bloomberg users. The mobile version supports 11 languages (including Ukrainian and Chinese) and lets you see expanded versions of charts by rotating your iPhone.
• iXpenseIt
  Cost: $4.99
  This app provides much of the same expense-tracking and recording functionality as Expense2GO, only it isn’t necessary to be a Salesforce.com user. Features include records export, expense summary, one-time setup for recurring expenses, graphical reports, password protection, text search and a world currency list. This app is also available in a free “Lite” version that limits the user to 10 expense records.
• Oracle Business Indicators
  Cost: Free
  Want to see a list of your top 10 customers, by profit, while on the road? This Oracle application allows users to view analytics from across the scope of their business, whether in the financial, human resources, supply chain or customer management areas. Users can also browse and search through business performance metrics. The free application requires licensing of Oracle Business Intelligence Suite Enterprise Edition Plus or Oracle Business Intelligence Applications or both.
• FTP On The Go
  Cost: $9.99
  This FTP client for the iPhone and iPod Touch, created by Headlight Software, lets IT administrators make adjustments to a Website and view files on the FTP server even while on the road. The application also features a built-in text editor, and users can download photos for later viewing and editing. Images can be uploaded to the server from the iPhone’s photo library.
• FlightTrack
  Cost: $4.99
  In addition to providing real-time flight status, weather radar updates, route maps and push alerts, this app lets users check gate numbers, delays and cancellations, and search by aircraft type, speed and altitude. Fun side-feature: Shake the iPhone to follow a random flight.
• Go Green
  Cost: Free
  Find tips on how to live a more efficient lifestyle. The more tips you earn, the more your Green Status increases, showing that you’re making a difference (however small) for the environment.
• Cheap Gas
  Cost: Free
  Find the cheapest gas in any given area, down to the prices for all grades and the distance to nearby stations. You can also sort gas station results by distance or price.
• Salesforce.com Mobile
  Cost: Free
  This app from Salesforce.com will synchronize Salesforce CRM with Microsoft Outlook address books, calendars and e-mail.
• Remote Desktop Lite
  Cost: Free
  This app provides secure access to a PC running Windows 7, XP Professional or Vista. Secure access to a work computer is provided via Wi-Fi or EDGE network, giving access to files, programs and other resources.

For full story, see http://www.eweek.com/c/a/Mobile-and-Wireless/The-Top-20-iPhone-Apps-of-2009-469150/?kc=EWKNLEDP12212009A