Hausa Language - Wikipedia article. - http://en.wikipedia.org/wiki/Hausa_language
Teach Yourself Hausa - Introduction to the Hausa language, including the basics of its phonetics and grammar, and some sample sentences illustrating everyday conversation in the language. - http://www.teachyourselfhausa.com
The Hausa Language - by Paul Newman - Write-up on a reference grammar of the Hausa language, by one of the top authorities in the field, and published by Yale University Press. - http://www.yale.edu/yup/books/081898.htm
Ethnologue Report for Hausa - Information about where Hausa is spoken and the number of its speakers. - http://www.ethnologue.com/show_language.asp?code=HUA
UCLA Hausa Page - UCLA resource guide to the Hausa language and the culture of Hause speakers. Includes an online Hausa grammar. - http://www.humnet.ucla.edu/humnet/aflang/Hausa/hausa.html