Many users find online storage accounts ("cloud" storage) useful to upload documents, music, Powerpoints, etc. so that they -- or others -- can access from anywhere in the world. Such cloud storage also provides an additional form of backup storage (although I would always have a portable backup to the data on your PC.
Problem 1: Cloud storage is expensive. Most sites provide only a few GB for free and then charge you for more (Dropbox costs $120/year!).
Solution: Windows Live Skydrive. For the cost of a Live or Hotmail account (free), you can use that Live username/password to log on and create a Skydrive account with 25GB of free storage per account.
Problem 2: Skydrive allows you to create folders (and subfolders) but uploading is one file at a time with any browser other than Internet Explorer.
Solution: SDExplorer (formerly Skydrive Explorer). SDExplorer is a small but powerful tool that creates a new drive on you Windows Explorer shell (the "tree" you use all day long to copy/cut/paste between folders). On my PC, it appears as a new drive "G" and shows all the folders that I have online -- without having to open a browser!
Here is the productivity boost: open your Windows Explorer and you can simply copy, drag-and-drop, or paste files from your PC to the SDExplorer (online) drive. The changes take effect immediately up in the "cloud." You can also create a new folder on your SDExplorer drive with a simple right-click. And you can delete folders that you have online from your SDExplorer drive.
The Pro version has a few additional features (including no more 50MB cap on single file size uploads). SDExplorer costs $13 for a lifetime license.
Free or Pro, this is a useful little tool to have on your PC.
REVIEWS:
http://lifehacker.com/5433481/skydrive-explorer-mounts-your-skydrive-in-windows-explorer
http://www.washingtonpost.com/wp-dyn/content/article/2010/02/18/AR2010021804606.html
http://www.downloadsquad.com/2009/10/30/access-skydrive-from-windows-explorer-my-computer/
Note: If you tried an early version of this program and it didn't work, the latest versions 2.1+ are very stable and polished).