Larry Miller (the doorman from that Seinfeld episode "The Doorman") has an excellent piece in the Weekly Standard that comments on the fortitude of our current Congress in the face of an implacable enemy.
"Here I am" is a powerful and layered statement, but there's another meaning to hineni, even deeper and more resonant: Here I stand.
Here I stand. It's not a meek thought; it's a bottom line. "Here I stand. Here I will make my stand. I know what will most likely happen, but it does not matter, since I will not be moving. This is where I am going to make my stand. Hineni."