Some example of simple styled button

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Default Button" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/ic_launcher"
        android:text="Button with background of drawable, no CLICK visual effect" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="#550000ff"
        android:text="Button with background of color, no CLICK visual effect" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:drawableRight="@drawable/ic_launcher"
        android:text="Button with drawableRight" />

    <ImageButton
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />

    <Button
        style="?android:attr/borderlessButtonStyle"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Button with borderlessButtonStyle (for API 11+)" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:shadowColor="#000000"
        android:shadowDx="5"
        android:shadowDy="5"
        android:shadowRadius="10"
        android:text="Button with shadow on Text" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:shadowColor="#000000"
        android:text="Button with Styled Text"
        android:textStyle="bold|italic" />

</LinearLayout>