Here’s my layout file:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/yellow" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<include
android:id="@+id/header"
layout="@layout/header" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginTop="10dp"
android:background="@drawable/green"
android:orientation="vertical" >
<TextView/>
<TextView/>
<TextView/>
<TextView/>
</LinearLayout>
</LinearLayout>
</ScrollView>
And here’s how it looks:

Blue is header, Yellow is ScrollView and Green is LinearLayout which I want to fill the space marked with red arrow.
I use one more LinearLayout which contains the header and green LinearLayout in order to use ScrollView.
Problem: How do I make Green LinearLayout fill the entire space to the bottom?
On the ScrollView, try to set the fill viewport to true.
You can do it either by xml or code.
http://developer.android.com/reference/android/widget/ScrollView.html#setFillViewport(boolean)