A site "for students and educators in business studies, economics, accounting, leisure, sport & recreation and travel & tourism" - and not one primarily intended for business English per se. The huge collection of material on this site will probably repay the time you invest in finding what is going to be of most interest to your own learners.
How to teach Business English using the Internet (Onestopenglish.net) Publisher Macmillan has a useful page of ideas and links for anyone who suddenly finds themselves teaching business English.
Needs analysis (also from Onestopenglish.net).
Macmillan also now has a dedicated Business English site.
Market Leader (business English coursebook)
Many course books now have their own dedicated website on which you will find resources. Longman's excellent Market Leader series is one.
About using case studies in teaching BE (see also further case study sites below).
The BBC has a business news audio bulletin - great for 5 minutes listening practice a day... It also has a business news section - great for 5 minutes reading practice a day!
Business English "Words in the News" From the BBC's learning English section. More from the BBC's learning (business) English section.
Financial news headlines from Yahoo!
Some (not very interactive) Business English exercises.
Spanish-English business online glossary (Andy Miles).
You will find more online dictionaries on the IH Barcelona translation site.
Newspapers, including general broadsheets like The Guardian or The Times have their business sections, which are obvious sources of information of interest to your learners, as well as of the lexis of Business English.
Case studies Material designed for business students and teachers.
More case studies (from Bized, see above).
The Internet TESL Journal also has a BE links page.