Scrabble3D is a highly customizable Scrabble game that not only supports Classic Scrabble and Superscrabble but also 3D games and own boards. You can play local against the computer or connect to a game server to find other players.
Great work Scotty, thank you. Previously my mum played an ancient Windows version which I could only get working (on Linux) in a Win98 virtual machine. Your version is much better in so many ways. She particularly likes the word definitions in 'tool tips' feature. She's 88. Perhaps one of its most elderly users. :)