I was going to say Trie but it was the first response to the SO thread so I guess it wasn't as little known as I thought. I implemented it because I was making

I was going to say Trie but it was the first response to the SO thread so I guess it wasn't as little known as I thought. I implemented it because I was making a game that had scrabble elements in it and needed to check ahead to see if the player had a word that could still take letters (a prefix) or if they'd hit a dead end. Fit the whole SOWPODS into a remarkably tiny space with millisecond lookups. Probably my favourite part of the project.