Evernote is both an App and a website that I find very useful to use because Evernote works on just about EVERY device or computer you can find.
"Device-agnostic" is the term I use for tools that work on any device and I can count on everyone having access to. Device-agnostic technology is great to start using today because you don't need to depend upon having an iPad, iPhone, Android, or other particular device to utilize the tools.
Why to use Evernote on iPad:
Evernote.com as a writing and organization tool:
~60 seconds each