Lost loves segments, the kind where people were looking for someone they crossed paths with, such as saving their lives from a car accident or some other dangerous situation.

Can anyone give me as many examples as possible for this kind of segment?

It's interesting for people to search for unidentified individuals, but for good things, instead of crimes.

http://unsolvedmysteries.wikia.com/wiki/Lost_Loved_Ones

This lists missing persons as well as "lost loves" so it's not all about looking up people for happy memories rather than violent crimes. There are a lot of cases listed though, so there should be some of the good stories included.