Welcome
When you first visit OneDrive.com you'll see this explanatory video and quick wizard at the top to take you through its features.
Share
You can share via a web link or share to another OneDrive user for collaboration.
Shared
Here you can see files that have been shared for collaboration.
Access PC
OneDrive is the only product I know of that will let you access any file on a PC where it's installed via the web.
All Photos
Photo presentation is clear and attractive, starting with the date based All Photos view.
Photo
The dark background lets the photos shine, and extras include tagging of keywords, people, and places. There are even comments!
People and Map
This shot shows people tagging and the sidebar map based on the photos GPS data.
Windows Phone
As you might expect, the Windows Phone app is the most powerful OneDrive mobile client, with search, but still no music streaming.
Android
The Android app now lets you auto-upload photos and videos.
iPhone
The iPhone app also offers auto-photo-uploading, with videos, too, unlike iCloud. The bad: No search.
Office 365 Integration
OneDrive is built into Office 365 applications as the default save location, and that's not a bad thing.
Manage Storage
This page shows you how much OneDrive storage you have.
More Storage
You can buy more storage at better prices than most of the big cloud competitors.
Office Web App
OneDrive is where you open and save documents you work on in Office Web Apps.
File System
On Windows 7 and the Windows 8.1 desktop, OneDrive folders can be worked with in the File Explorer just like any other local files.
OneDrive (SkyDrive) on Mac OS X
The OneDrive client software for Mac OS X appears in Finder.