And the Pièce de résistance in the series of Dr. Horrible Act I lyrics and chords/tabs: A Man’s Gotta Do, What a Man’s Gotta Do. (wikipedia suggests that this page is related)

(Dr. Horrible)
 
Ebm       Ab               Bbm
  A man's gotta do, what a man's gotta do
Ebm     Ab                   Bbm
  Don't plan the plan if you can't follow through
Gb               Ab             Bbm
All that matters taking matters into your own hands
Ebm               Fm
Soon I'll control everything,
Gb   Ab
  my wish is your comm...
 
(Captain Hammerman)
Eb
Stand back everyone
Fm
Nothing here to see
     Ab
Just imminent danger
           Ab           Bb
And in the middle of it me
     Eb
Yes, Captain Hammer's here
Fm
hair blowing in the breeze
    Ab                  Bb
the day needs my saving expertise
  Fm    Bb               Cm
A man's gotta do, what a man's gotta do
   Fm    Bb                 Cm
It seems destiny, ends with me saving you
    Fm               Bb             Cm
The only doom that's looming is you loving me to death
Bb    Ab                 Bb                Eb
      So I'll give you a sec to catch your breath
Thank You Hammerman:

(Penny)
 
Eb
Thank you Hammerman
Fm
I don't think I can
Bb 
Explain how important it was
Ab                   Bb
that you stopped the van
Eb
I would be splattered
Fm
I'd be crushed into debris
Bb                   Bb7
Thank sir for saving me

Reprise:

Captain Hammerman
Penny
Dr. Horrible

  Fm    Bb               Cm
A man's gotta do, what a man's gotta do
You came from above
Are you kidding?
   Fm    Bb                 Cm
It seems destiny, ends with me saving you
I wonder what you're captain of
What heist were you watching? Stop looking at her like that!
Fm   Bb                         Cm
When you're the best, you can't rest, what's the use
My heart is beating like a drum
Did you notice that he threw you in the garbage?
    Fm        Bb                   Cm
There's ass needs kicking, some ticking bomb to defuse
(I Must be in shock)?
I stopped the van! The remote control was in my hand
    Fm               Bb             Cm
The only doom that's looming is you loving me to death
Assuming I'm not loving you to death
Whatever
Ab                  Bb              Eb
So please give me a sec to catch my breath
So please give me a sec to catch my breath
Balls.