1. ReCAPTCHA
The reCAPTCHA 庫讓你可以為網站創建高級的CAPTCHA系統，這個系統其實是用來生成驗證信息的，甚至包括語音驗證，下圖就是個好例子。
當然還有reCAPTCHA 服務可以使用，其提供易用的免費API，值得在你的網站試試。
The reCAPTCHA library allows you to integrate an advanced CAPTCHA system on your website, which helps keep spam bots from posting on your website. The visual CAPTCHA also includes a helpful audio feature.
In addition to the reCAPTCHA service, the library also includes an API for the "Mailhide" service which hides emails from spammers.
The API is free and easy to implement on your site and also gives back to the community as it translates scanned books.
下載 ReCAPTCHA | 獲得 API Key | 文檔
2. Akismet
Akismet 是個供小站點使用的免費服務，用來修改規范將加入數據庫的評論（防止惡意評論）。這個庫一直在改善。
Akismet is a free service that can be used on most small sites - or used on larger sites for a small fee. The library works by comparing comments to a database of existing spam comments provided by other users. The library can then decide to flag the comment for moderation or allow it through. Everyday the library grows and the service improves.
介紹 Akismet
3. Services_JSON
JSON是人類能容易理解的信息傳遞格式。不過如果你並未使用5.2.0以後版本的PHP（從那以後PHP有了JSON官方支持），那麼就應該試試這個庫。
JSON is a handy format for transmitting human readable data. Not everyone has made the move to PHP5 which has included JSON support since version 5.2.0. This small library enables you to implement JSON functionality into your own applications if you are not using a recent version of PHP.
查看 Services_JSON
4. Smarty
Smarty就是鼎鼎大名的官方模版庫了。它提供了不少有用的功能。其實使用PHP的人都該瞧瞧。
Smarty is a template engine which was formally a sub-project of the PHP project. Smarty provides many powerful features such as loops, variables, and a great caching system. The library has many years under its belt and is nearing its version three release.
下載 Smarty | 觀看文檔
5. pChart
pChart是極其有名的數據圖形庫。它能為數據展示提供各種美麗的圖表。其實使用PHP的人都一定會碰到使用它的情況。
In addition to displaying text data in your application, it can also be useful to show data in a more visual format. This can be done with a slew of options like pIE charts and bar graphs.
pChart is a script that allows you to create charts and graphs from SQL querIEs or manually provided details. The script is baked by GD to create the images. There is also a main focus on the aesthetics; so it creates some beautiful work.
下載 pChart | 查看文檔| VIEw Demos
6. SimplePIE
SimplePIE 讓你輕松提取內容（好比RSS feeds)。它能和多種語言交互，也能處理各種格式的feed。
SimplePie allows you to easily pull in syndicated content (like RSS feeds). It's also been integrated with a lot of different platforms and language sets; it should be able to deal almost any feed in a varIEty of ways.
下載 SimplePIE | 查看文檔| 為獨特的RSS Feeds拓展SimplePIE
7. XML-RPC PHP Library
有時你需要使用XML-RPC技術去和其他網站交互，那麼試試這個XML-RPC PHP 庫吧。
Applications sometimes use functionality to "ping" other sites when an action has occurred (known as trackbacks). This is done by using a protocol called XML-RPC. The
XML-RPC PHP library also allows you to integrate the functionality into your website.
下載 XML-RPC PHP | 查看文檔
8. Amazon S3
Amazon有名的雲計算平台叫做“S3”。這裡就有Amazon S3 庫 讓你不用任何附加工具就可以使用雲，上傳大量數據文件。
Amazon provides a nice service to work in the cloud, called "S3". Nettuts+ even uses it to store the images seen in each article. There is a nice
Amazon S3 library that doesn't require any third party tools and allows for large file uploads.
下載 Amazon S3 PHP Class
9. PHPMailer
大多數web應用都在使用php的mail()函數。PHPMailer讓你更加靈活地處理Email的發出，不但支持任何格式，還可以加入附件並自定義header。
Most applications send out an email in some form, but usually rely on the basic php mail() function. PHPMailer is an existing powerful class that allows you to send different types of emails - from basic text to rich formatted emails. These emails can also include attachments or custom headers.
下載 PHPMailer | 查看文檔
