Magento: Display products from a certain category

If you want to display a certain category on a page, add this code on the design tab

<reference name="content">
  <block type="catalog/product_list" name="featured" template="catalog/product/list.phtml">
      <action method="setCategoryId"><category_id>[category id here]</category_id></action>
  </block>
</reference>

and then replace [category id here] with your category id.