Navigating in the Solution Explorer

Ctrl + Alt + L: Open the Solution Explorer (the most important one).

Esc: Return focus to the coding window (hides the solution explorer).

Up Arrow: Move up between nodes.

Down Arrow: Move down between nodes.

Right Arrow: Expand current node.

Left Arrow: Collapse current node.

Solution Explorer Project Actions

Ctrl + Shift + A: Add a new item (project must be highlighted).

Shift + Alt + A: Add an existing item (project must be highlighted).

Alt + P + R: Add Reference to the current project.

Alt + P + E: Add Web Reference.

Alt + P + A: Set the current project as the starup project.

Alt + P + P: View the current project's properties.

If you have any others related to the solution explorer windows please post them in the comments.