SSMS is really keyboard friendly, and you have keyboard shortcuts for pretty much any functionality that is exposed via the various menus. You can configure them according to your preferences under Tools->Options->Environment->Keyboard. Here are 10 areas that you should definitely be familiar with:

• Change Selected Database
  Ctrl + U: Once you are in the Sql Editor, pressing Ctrl + U selects the database dropdown in the Sql Editor toolbar. You can then use the arrow keys to change your current database, and pressing the Esc key takes you back to the editor.

• Display Estimated Query Execution plan: Ctrl + L

• Toggle Results Pane: Ctrl + R

• Insert Code Snippets: Ctrl + K, Ctrl + X

• Activate Autocomplete: Ctrl + Space

• Clipboard ring
  Ctrl + Shift + V: Cycle through clipboard ring.

• Navigate in code editor
  Ctrl + ]: Navigate to matching parenthesis
  Ctrl + –: Navigate to last cursor location
  Ctrl + Shift + –: Navigate forward to cursor location

• Comment code
  Ctrl + K, Ctrl + C: Comments selected text
  Ctrl + K, Ctrl + U: Uncomments selected text

• Bookmark
  Ctrl + K, Ctrl + K: Toggle Bookmark
  Ctrl + K, Ctrl + N: Go to Next Bookmark

• Enter Full Screen
  Shift + Alt + Enter: View Code Editor in Full Screen

For a complete list of SSMS keyboard shortcuts, see the MSDN article.