[tyler]

Two useful implementations that this article misses are Array-compacted tries (aka dual-array tries) and Array-mapped tries. ACTs are nice due to the small memory footprint and good cache-locality, but have the downside of being difficult and time-consuming to construct. AMTs have a bit-array for determining existence of children and a sorted array of child-pointers in each node and are surprisingly fast at both insertion and search. Both have been described elsewhere, but I like the explanations by Phil Bagwell in his paper, "Fast And Space Efficient Trie Searches" (1998).