I find that one of the best ways to stay informed about positive things is to try to find a website that deals with what ever it is you want to know
for example, I know a woman who subscribes to a website about cats and often shares with people in her email addressbook positive cat stories

also, their's google alerts. if you google alert the right thing, you can get some good stories.

one of mine is "weird news", some of those are pretty cool

another thing (slightly weirder) is finding a news source for children

kids news outlets tend not to dwell on the deeper stuff as much (A because kids won't understand, B because it's a kid audience and they want to share things kids are interested in).

just some ideas