Select current word

One of the things I use most since I discovered this, is using Command+D to select the current word. The scenario in which I use this a lot is to replace a word with a word I already have somewhere else:

1. Select word you want to copy (Command+D, Command+C)
2. Replace other word with copied word (Command+D, Command+V)

Magic happens when you do this with multiple cursors on multiple lines that are similar.

Another neat trick with Command+D is to use it repetitively. This will incrementally select all occurrences of the word your cursor is on, starting with the closest.