Is there an easy way to have an image in a radio button label? I have a dynamic list of images, that I want to have a user select via associated radio button in a form. Is there an a way I can do this with the base form api, or is this the kind of thing I'd need to create a custom theme for?
You can do this using CSS.

Add appropriated class from $form then use CSS to add images as background-image.

For example:

$form['example'] = array(
  '#type' =&gt; 'radios',
  '#title' =&gt; t('example'),
  '#default_value' =&gt; 1,
  '#options' =&gt; array(0 =&gt; ('Value 0'), 1 =&gt; ('Value 1')),
);


CSS

.form-item-example &gt; labela[for=edit-example-0]{
      background-image: url('/path/to/image-0.png');
}