The Extend Selection feature allows you to successively select expanding blocks of code so that you can easily select any expression in the code
by placing the caret somewhere inside it and pressing Ctrl+W a few times (alternatively, choose ReSharper | Edit | Extend Selection):
Shrink Selection does exactly the opposite. Press Ctrl+Shift+W or choose ReSharper | Edit | Shrink Selection.
For guidelines on how to configure this feature to take CamelCase into account, see