Linchpins

I'm reading a book by Seth Godin right now, called Linchpin.  The premise is how to become indispensable as an employee.  What things can I do in order to make myself a critical part of the puzzle? This has me thinking on several different levels, here are some the questions I'm asking of myself:

1.  What can I do today in order to ADD VALUE?

2.  Who can I encourage and help do better today?

3.  If my boss works for me, what would I have him do so I can do my job better?

What about you?  Do you find that you are an invaluable part of the team, irreplaceable, or are you just going through the motions to get your job done?