Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
Interleave is a Web-enabled business process automation application. It enables you to model your business process like purchasing, project management, and contract management and make it available online. It's meant to replace processes which currently rely on paper, email, or spreadsheets and it has a very good workflow engine. You can create invoices, export to RTF and PDF based on templates, export to MS Excel, interpret incoming email, and publish your data to the Web.
LimeSurvey (formerly PHPSurveyor) is a Web application that interacts with MySQL, MSSQL, or Postgres to develop surveys, publish surveys, and collect responses to surveys. Once a survey has been created, data can be inserted into the survey either by a "pretty" public screen which presents each question one at a time, or by a quick and nasty data entry screen. It includes the capacity to generate individualized "tokens", so that invitations can be issued to participants. It also has the capacity to set conditions on whether questions will display (branching), numerous question types, and a basic statistics function.
PortaBase is a database program for creating, browsing, and editing single-table data files. Notable features include the ability to change the columns at any time, views of column subsets, multi-column sorting, multi-condition filtering, CSV import and export, XML import and export, and column summary statistics. Typical uses are media inventories, reference charts, shopping lists, and TODO lists.
phlyMail is a groupware, webmailer, and PIM. It offers unlimited nested groups, unlimited POP3/IMAP profiles, quotas, an integrated address book, a calendar with multiple reminders and event repetitions, a file manager with an integrated WebDAV server, the ability to send faxes, SMS support (which lets you send SMS, get reminded of events via SMS, and get email notification via SMS), a bookmark manager, themes, and multilingual support. It uses either sendmail or SMTP to send email, and can handle MIME and SSL connections. Support for IDN (Internationalized Domain Names) is included. Through its modular design, it's easy to add completely new features as modules, which can be plugged into the system.
Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.