Take Two (also known as Speed Scrabble) is wonderful Scrabble variant. There is no waiting, nobody taking your perfect spot, and no holds barred.
At the start of the game, you will be given 7 tiles in the upper left hand bin. Arrange these tiles in the playing area (large area on the right) in a typical Scrabble pattern. Once you've used all your tiles in an intersecting pattern, click the take two button to recieve 2 more tiles. Incorporate these tiles into your pattern, rearranging where necessary.
If you're stuck, wait for the countdown timer to get two new tiles.