Places to look for texts and corpora

• European Language Resources Association
• Linguistic Data Consortium
• International Computer Archive of Modern and Medieval English
• TELRI Research Archive of Computational Tools and Resources
• The Oxford Text Archive
• Project Gutenberg (free texts)
• British National Corpus
• International Corpus of English (ICE)
• COBUILD - Bank of English
• EServer
• Reuters corpus

Sites with useful information

• W3-Corpora
• Corpus Resources - Yukio Tono
• List of Corpora and resources from University of Tübingen
• Bookmarks for Corpus-based Linguists - David Lee

You can also use one of the major search engines and search for the word corpora and the name of the language.

Example
English+Corpora with Google
Spanish+Corpora with Google
French+Corpora with Google
Italian+Corpora with Google
Portuguese+Corpora with Google

Knut Hofland
Computational Language Unit (CLU)
Uni Computing
Uni Research AS