iGoogle was on my 2006 list at #10. At the time I wrote that I had been using it for 6 months and liked it. Now I can say that I've been using it as my browser start page for 18 months and I like it even more than before.
WikiHow has a short tutorial on using iGoogle.
NCAS has a nice series of screenshots and explanations.
Here's a little screencast embedded below. This is a case of using Tool #7 (and CamStudio) to show Tool #6. You can click on the video below to play it on this page, or go to the page at Blip.tv where the video displays at a larger size and where you also have a full screen viewing option.
I'm going to also embed another video. From Google Channel Japan comes this video from their YouTube account.Yes, it is in Japanese, but think you'll be able to follow along anyway. It's fun and well done.
Other popular alternatives include Pageflakes and Netvibes. I've used them both, but like iGoogle better.