When developing something in a language that you're not so experienced with, looking for the examples and digging them deeply is a good way of learning.

Same with the iPhone application development and considering it is something new for many developers, viewing the codes of real-world applications and re-using them when needed is very valuable.

Here are 20+ open source iPhone apps to learn and get inspired from:

Touch Gallery is a jQuery image gallery plugin which brings the native look and feel of native photo-viewing applications to the mobile browsers.

It supports browsing through the images with gestures and also works with desktop browsers with limited functionality.

The gallery depends on two other plugins: transform and activity-indicator where both is included in the download package.

Few days ago, the jQuery team announced that they are working on jQuery Mobile which will probably become quickly popular on creating mobile web apps. for the fans of the library.

On the other hand, there are already ready-to-use solutions like the pretty-complete jQuery iPhone UI (check the "Mobile Development" category for others).

It is a jQuery library which emulates the iPhone interface that is handy for creating iPhone web applications.

The library includes widgets like menu, tabs, scrolling, forms and gallery browsing.

jQuery iPhone UI is not complicated to use and comes with a documentation to get you started.

ShareKit is an open source package for quickly adding share features to any iOS application with just 3 lines of code.

It supports popular services like Delicious, Twitter, Facebook, Google Reader, e-mail and more.

The kit enables sharing images, URLs or files and only displays the appropriate services for the type of the content.

ShareKit has a customizable UI to match the look of your application and it works offline as well (sends the pending items when there is a connection).

Sencha (previously known as Ext JS) has released Sencha Touch, an HTML5 Mobile App. Framework, which allows you to develop web applications that look and feel native on Apple iOS and Google Android touchscreen devices.

It makes use of HTML5 for delivering audio/video or localStorage and CSS3 for maximum styling like rounded corners, background gradients, and shadows.

The code created is resolution independent. It uses a method which allows developers to change the overall scale of their interfaces on the fly with no pixellation.

Sencha Touch has a powerful animation system that makes flexible animations between screens and views possible.

Slide, pop, and fade animations are included with the library, each with a robust set of options to change attributes like direction and masking style.

And, as they are created with CSS, building custom animations is a joy.

Also, it includes a set of common icons for using them in toolbars and tab bars.

InAppSettingsKit is an open source solution for iPhone app. developers to easily add in-app settings to iPhone applications.

It offers an hybrid approach by maintaining the Settings.app pane, so, user can decide where to change the settings.

The kit can be integrated into any iPhone application easily (but may require tiny updates).

Although the intention of InAppSettingsKit is to create a 100% imitation of the Settings.app behavior, there are few more features provided like "overriding the settings file that is used in-app".

Rhodes is an open source framework for building native applications for all major smartphone operating systems: iPhone, Windows Mobile, RIM, Symbian and Android using Ruby as the development language.

It has access to native device capabilities such as GPS geolocation, PIM contact reading/writing and camera image capture.

Development process can be called as "easier" with Rhodes as most of your UI customization can be done in HTML templates.

There are integrated styling libraries for matching the look and feel of native applications (ex: for iPhone, it is based on iUI and jQTouch can be used as well).

MoSync is an open source SDK, with many tightly integrated components, for creating cross-platform mobile applications.

It includes compilers, runtimes, libraries, a device profile database, an emulator and more.

The kit is has an Eclipse-based IDE for C/C++ application development and comes with a detailed documentation.

Some of the built-in libraries are: graphics, audio, multimedia and TCP/HTTP/Bluetooth/SMS which enables you to interact with almost every features of mobile platforms including:

• Android Cupcake 1.5
• Java ME MIDP 2 (J2ME)
• Moblin 2.x
• Pocket PC 2003
• Smartphone 2003
• Symbian S60 2nd, 3rd, and 5th ed
• Windows Mobile 5.0-6.5

and others like iPhone, Blackberry, MeeGo are to be included.

To sum up, the kit is great for anyone who wants to develop for multiple mobile platforms with the same tools and logic.

MobiOne is a powerful and free iPhone and Palm Pre emulator (currently for Windows only) with a drag-n-drop mobile-web visual designer for mockups and mobile HTML code generation functionality.

It has various mobile design templates, updated OSS components, screen capture, multi-touch, gesture support and more.

The tool doesn't require any SDK to be installed as it takes advantage of HTML5, CSS3 and JavaScript for development.

MobiOne also supports PhoneGap (an open source, JS-based mobile development toolkit)

PassShark is a MooTools class for masking password fields similar to iPhone: showing the last typed character for a while & masking it later.

It is an install-then-forget solution as after inserting the passshark.js file into your website, the class will be finding the password fields automatically & applying the masking.

PassShark has few option like defining the "interval it checks for the newly enteres characters" or "the character inputs are replaced with".

It is an unobtrusive class & works in all major browsers.