I've kept my saving in a single, high interest account for a while now. It works particularly well as a contractor in that I can put aside tax and GST and earn interest on that before I have to pay it to the government.
It has been a bit difficult to keep track of how much money was saving, and how much was tax/GST though, so I've written a simple app to keep track.
Fundation lets you set up funds to manage your saving. Each paycheck can be automatically divided up into the different funds in ratios you specify.
If you have any errors in Fundation, or any suggestions for improvements, please use the comments of this post to provide them.