1) Wikipedia (in featured box),
2,3) Some Exchange/Notes migration software called "Binary Tree" that owns binarytree.com,
4) cslibrary.stanford.edu on binary trees w/exercises,
5) "Binary Trees in C++" from cprogramming.com,
6) "Binary Tree" at dictionary.reference.com, and
7) "Binary Tree" on mathworld.wolfram.com
You've got to admit that 2 and 3 are pretty glaringly bad in this case. My fold ends halfway through 5. Half of the top 4 links are for the data structure, half for some irrelevant company, so DDG is effectively placing this company on par with the data structure. If you didn't know quite what you were looking for in advance, this could lead to serious confusion.
For me:
1) Wikipedia (in featured box), 2,3) Some Exchange/Notes migration software called "Binary Tree" that owns binarytree.com, 4) cslibrary.stanford.edu on binary trees w/exercises, 5) "Binary Trees in C++" from cprogramming.com, 6) "Binary Tree" at dictionary.reference.com, and 7) "Binary Tree" on mathworld.wolfram.com
...above the fold.