Zoho is an online office suite.  It contains a word processor, spreadsheet program, slide presentation program, and lots of other management oriented programs.

The advantage that programs like Zoho provide students and teachers is they are cross platform, and you can access your data anywhere. 

What Zoho does that programs like OpenOffice and Microsoft Office don't do is give users the ability to share documents.  You can set other users as collaborators or you can publish your files as webpages.