Official Gmail Blog: Find great stuff to read in Google Reader
Create your own reading list (of your interest):Google Reader
Let say how to save time using Google reader
Say you are interested in reading news from different websites like website Times of India, Headlinedstoday, Google news, ndtv, samachar, zeenews, Indiaexpress. you have to visit different websites . Use Google Reader , in one window you can get news from all these website at one place.
Well that's one of the thousand such uses of Google Reader I gave .
So still not using, then you are missing a lot to time saving,use Google Reader