Actually, Weather Undergound is owned by IBM. In some ways, it is not as good as when it was owned by the original founders, but it is still the go-to site that I use for checking radar. They have a product that I use virtually everyday -- it is a graphical tool called a "Wundermap" that makes reading radar returns on-the-fly a breeze.
For example here is the page for Sarnia, Ontario and on this page you can look at current conditions, by the hour, 10-day predictions and the Wundermap link.
Mark