View Relationship Between 2 people other than yourself
A major roadblock I see is not being able to search the relationship between 2 people that may or may not be related to me. You can already view "my relationship" with somebody but why can't I enter information for 2 other individuals that share same last name or are believed to be related otherwise and see how they are related to each other.
A lot of the hints and clues used to find the right person to tie in to a tree comes from association with or relation to others with more known documentation.
I think this feature would be immensely helpful in finding and connecting people.
Think of it like google maps directions feature where you are asked to enter the destination and the starting location and it links the 2 together.
You could just build a simple data entry field asking for the info already requested in the "Find" feature on the site but have 2 of these and a button saying see their connection.