Zoho Planner is part of Zoho's suite of productivity tools (read more about them here). With Zoho Planner you can create to-do lists, notes, upload images and files add email reminders and access your data anywhere. You can create To Dos, Appointments (calendar), and Reminders and set reminders for each one (will email you).
You can create a page where you can create your to dos, appointments, notes, and files and make the page available to others. You also have a section for pages that were shared with you, your To Do list and Appointments, attached files and even tag your page.
You can share and collaborate on notes and tasks lists in Zoho planner too.
It's similar in function to Evernote and Google's applications and is a good alternative to them if you are looking for something different.
Students can also use it to get organized.
Zoho - suite of on-line business, productivity & collaboration apps
Alternatives to Google's web services and apps
Google for Educators Resources
Evernote for Educators Resources