selfoss is an open source and lightweight web application that can fetch content from any number of sources.

RSS is the content type supported by default, however, with its plugin system, any new source types (log files, e-mails, etc.) can be implemented by adding a single class.

The application has a simple-yet-functional interface which also supports navigating via keyboard.

It is also flexible in means of the database used; you can either go with MySQL, SQLite or MongoDB.

For MySQL users, phpMyAdmin -the popular MySQL admin tool-, is probably one of the most-used apps unless you are fan of a desktop MySQL admin tool.

MyWebSQL is an exciting open source alternative to both as it is a web-based MySQL (and SQLite) manager with a desktop-like functionality.

It is built with PHP and, with the help of a completely Ajaxed interface, tasks can be accomplished pretty quickly.

Creating, editing and deleting tables or records are easily done in a grid mode which also makes working with multiple items at the same time possible. Also, shortcuts for any actions exist inside context menus to make browsing faster.

There are other must-have features like import-export, SQL editor (with syntax highlighting), repair tables, search, process manager, etc.

MyWebSQL is a multilanguage app with lots of ready-to-use languages and has a themable interface.

Imho, what is missing the most is the ability to manage multiple server connections with a single login and scheduled tasks (which I hope would exist in the future versions).

Yioop! is an open source search engine built with PHP and uses MySQL or SQLite for storing the data.

It can be configured to crawl any page it finds by following links or limited to any given number of URLs and used as an in-site search engine (like Google Custom Search).

A standard setup can crawl and index millions of pages per day and this number can be increased by running more crawlers (distributed setup is possible as well).

There is support for indexing many file types including HTML, DOC, PNG, JPG, GIF, XML, sitemaps, RSS and much more.

Also, the system can be controlled completely from a web-based administration interface.

SQLiteManager is an open source and web-based application for managing the popular server-less, zero-configuration SQLite databases.

It is built with PHP and can control multiple databases besides applying every action on tables or records.

Using the application, queries can be ran, MySQL queries can be converted to SQLite-compatible ones and triggers can be created/edited as well.

SQLiteManager has different skins and it is a multilingual resource with ready-to-use language files.

P.S. phpMyAdmin users will feel very comfortable as the interface is pretty similar.

Crystal is a database toolkit for PHP which aims to help developers build & scale reusable, database-dependent, framework-agnostic applications.

It has 3 independent components:

• Database wrapper – for CRUD operations
• Validation module – provides a comprehensive data validation
• Database manipulation module – used for creating databases, tables, etc.

The queries written with Crystal are database-independent which currently supports MySQL & PostgreSQL (SQLite is on the way).

For anyone who is familiar with SQL, learning Crystal wouldn't take no more than 5 minutes.

And, for many developers, it can be an option against framework-specific database layers like Zend_Db and Codeigniter's active record library or complex ORM's like Doctrine.

InDefero is an open source software forge application, built with PHP, that enables anyone to create a multi-project Google Code/Sourceforge-like system to manage their codes.

It eases tracking bugs, providing downloads, documentation and having an easy overview of the code base both for you & your team.

Also, it makes communicating with the user-base possible which is vital for a healthy development process.

InDefero has other powerful features like:

• every user has their personal dashboards
• code browser with git, Subversion & Mercurial support
• project timeline
• powerful search engine
• diff visualization of the commits
• inline display of text files from the repository with syntax highlighting
• & much more..

It requires a webserver supporting PHP as module or fast-cgi & PostgreSQL, SQLite or MySQL 4.1+ as the database to run.

myTinyTodo is a free to-do-list application with a very simple & clean interface.

The application is built with PHP & uses MySQL or SQLite for storing data

It has very nice features like:

• adding notes to tasks
• tags (and tag cloud)
• due dates (input format: y-m-d, m/d/y, d.m.y, m/d, d.m)
• priority (-1, 0, +1, +2)
• password protection
• sorting by priority or due date
• search
• smart syntax improves creation of tasks (usage: /priority/task/tags/)
• print-friendly CSS

myTinyTodo has a ready-to-use styling for mobile devices & comes with multilanguage support.

Tracks is a web based, advanced & open source to-do-list (getting things done) application built with Ruby on Rails.

It comes with a built-in web server (WEbrick) which makes it easier to run on your own computer or it can be installed to any Ruby on Rails enabled web server.

Application has a very slick interface & offers a high usability with drag’n drops & Ajaxed actions.

Tracks is a multi-user to-do-list application where everyone can have their own tasks.

Items can be categorized, proritized, scheduled & starred (for reaching them easier).

With a chart-supported statistics page, you can see the progress of your tasks, analyze them better like finding out which are your productive days, which task took more then expected & more.

The application has a powerful feed support (text, iCal and RSS). You can subscribe to a list & get status updates for them.

Tracks also makes it possible to getting integrated with other apps. with its API. And, it provides a lightweight interface for mobile phones at  http://tarcksurl/mobile/.

Frog CMS is a simple yet powerful content management system. It is the PHP variant of Radiant CMS (Ruby on Rails CMS app. – see WRD post) with a similar interface and logic.

This CMS application is ideal to be used both by designers & developers as, in general, they already know the basics of PHP and can insert simple loop, if else type codes while creating the pages and Frog CMS lets code usage in certain places. On the other hand end-users can use it too as it has a HTML editor for contents.

Some features of Frog CMS:

• Unlimited hierarchically structured page navigation menu
• Flexible page content: body, sidebar, extended, summary
• Per page layout customization
• Simple and reusable content snippets
• Drag and drop page ordering
• Password protected administration
• Simple user and permission management
• File manager

For storing data, you can choose between MySQL database or SQLite 3 with PDO.