DHTML table which supports multi-row collapsing
HotScript @ RoŲnašn index for more scripts and extensions.
Run this script as an example.
<style type="text/css">
  tbody.closed .details {display:none;}
  tbody.closed .link_hide {display:none;}
  tbody.opened .link_show {display:none;}
</style>

<script type="text/javascript">
  function setParentNodeClass(currentNode, nodeTag, cssClass)
  {
    nodeTag = nodeTag.toUpperCase();
    while(currentNode.tagName != nodeTag)
    {
      if(!currentNode.parentNode)
        return false;
      currentNode = currentNode.parentNode;
    }
    currentNode.className = cssClass;
    return false;
  }
</script>

<table>
  <tbody class="closed">
    <tr>
      <td>Section 1</td>
      <td>
        <a class="link_hide" href="#HideDetails"
           onclick="return setParentNodeClass(this, 'tbody','closed');">Hide details</a>
        <a class="link_show" href="#ShowDetails"
           onclick="return setParentNodeClass(this, 'tbody','opened');">Show details</a>
      </td>
    </tr>
    <tr class="details"><td colspan="2">Details 1</td></tr>
    <tr class="details"><td colspan="2">Details 2</td></tr>
    <tr class="details"><td colspan="2">Details 3</td></tr>
    <tr class="details"><td colspan="2">Details 4</td></tr>
    <tr class="details"><td colspan="2">Details 5</td></tr>
    <tr class="details"><td colspan="2">Details 6</td></tr>
  </tbody>
  <tbody class="closed">
    <tr>
      <td>Section 2</td>
      <td>
        <a class="link_hide" href="#HideDetails"
           onclick="return setParentNodeClass(this, 'tbody','closed');">Hide details</a>
        <a class="link_show" href="#ShowDetails"
           onclick="return setParentNodeClass(this, 'tbody','opened');">Show details</a>
      </td>
    </tr>
    <tr class="details"><td colspan="2">Details 1</td></tr>
    <tr class="details"><td colspan="2">Details 2</td></tr>
    <tr class="details"><td colspan="2">Details 3</td></tr>
    <tr class="details"><td colspan="2">Details 4</td></tr>
    <tr class="details"><td colspan="2">Details 5</td></tr>
    <tr class="details"><td colspan="2">Details 6</td></tr>
  </tbody>
</table>