Find Nearest Neighbors in Any Space
Mathematica 6 has powerful and efficient nearest-neighbor algorithms, suitable for any dimension and any distance function.
In[1]:=  |  Graphics[Module[{r = RandomReal[1, {1000, 2}], nf},
nf = Nearest[r -> Automatic];
GraphicsComplex[r,
Table[{Line[Thread[{n, nf[r[[n]], 5]}]], Red, Point[n]}, {n,
1000}]]]] |
Out[1]=  |  |