Open Source language checker

LanguageTool is a rule-based language checker that will find errors for which a rule is defined in its XML configuration files or Java code.

You can think of LanguageTool as a tool to detect errors that a simple spell checker cannot detect, e.g. mixing up there/their, no/now etc. It can also detect some grammar mistakes. It does not include spell checking

It has been integrated in OpenOffice's latest 3.0 release, but can be used under 2.x also.

Install instructions in OpenOffice 3.x

Double click LanguageTool-0.9.4.oxt to install it. If that doesn't work, call Tools -> Extension Manager -> Add... to install it.
Close OpenOffice.org and re-start it.

For OpenOffice 2.x use LanguageTool-0.9.2.oxt instead.

More languages in Evolution

Evolution provides integrated mail, addressbook and calendaring functionality to users of the GNOME desktop.

Advantages

For me, there's only one reason I would use Evolution instead of Thunderbird:

• Evolution can use Outlook Exchange accounts (like the one I have to use in the office).

Disadvantages

• It is only for Linux systems.
• Insufficient edition possibilities when composing messages (no lists, no embedded images, ...)
  
• Simple filters didn't worked for me.
• Evolution can't be deinstalled from Ubuntu, because it is somehow linked to several applications, so uninstalling Evolution forces you to uninstall applications like Nautilus.
  This reminds me on IExplorer on Windows.

Tips & Tricks

More languages

By default, Evolution comes only with your systems language.
If you need more languages for spell checking, you have to install the corresponding aspell packages, for example:

sudo apt-get install aspell-de

Restart Evolution, and select the new languages for spell checking.