Microsoft Office 2010 Language Interface Packs are now available in 3 Nigerian languages, covering over 60 million speakers.
You can install them from here:
A Language Interface Pack allows you to change the user interface in the following Office 2010 applications: Excel, OneNote, InfoPath, Outlook, PowerPoint and Word. The pack includes a spell checker and is available for both 32-bit and 64-bit systems.
All three languages are already available for Windows 7 and Internet Explorer 9:
A few facts about these languages:
For more information on these 3 languages, check the Wikipedia page on Nigerian languages.
Language Distribution in Nigeria (source: Wikipedia):