How to put spacing between TBODY elements

Try this, if you don't mind not having borders.

<style>
table {
  border-collapse: collapse;
}

table tbody {
  border-top: 15px solid white;
}
</style>

<table>
    <tfoot>
        <tr><td>footer</td></tr>
    </tfoot>
    <tbody>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
    </tbody>
</table>

People will always have controversial opinions about using empty table elements to layout a page (as evidenced by this answer's downvote). I recognize this, but sometimes its easier to use them this way when you are working in a "quick and dirty" way.

I've used empty rows in past projects to space groups of table rows. I assigned the spacer rows a css class of their own and defined a height for that class that acted as a top and bottom margin for that group of table rows.

    .separator{
             height: 50px;
    }

   <table>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>

           <tr class="separator" colspan="2"></tr>

           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>

           <tr class="separator" colspan="2"></tr>

           tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
   </table>

If you don't have borders on your table cells, you could also define a height to your typical cell or row in your style sheet that evenly spaces out all rows of your table.

tr{
   height: 40px;
}

Here's another possibility that relies on :first-child which is not available in all browsers:

<style>
table {
  border-collapse: collapse;
}

td {
  border: 1px solid black;
}

tbody tr:first-child td {
  padding-top: 15px;
}

</style>

<table>
    <tfoot>
        <tr><td>footer</td></tr>
    </tfoot>
    <tbody>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
    </tbody>
</table>

Of all of the answers given above, only djenson47's answers retain separation of presentation and content. The drawback of the collapsed border model method is that you can no longer use the table's border or cellspacing attributes to separate the individual cells. You could argue that this is a good thing, and there are some workarounds, but it can be a pain. So I think the first-child method is the most elegant.

Alternatively, you could also set your TBODY class' overflow property to anything other than "visible." This method allows you to retain a separated borders model as well:

<style>
tbody {
    overflow: auto;
    border-top: 1px solid transparent;
}
</style>
<table>
    <tfoot>
        <tr><td>footer</td></tr>
    </tfoot>
    <tbody>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
    </tbody>
</table>

NEW ANSWER

You can use as many <tbody> tags as you like. I didn't realize that was ok by W3C until now. Not to say my below solution doesn't work (it does), but to do what you're trying to do, assign your <tbody> tags classes and then reference their individual <td> tags through CSS like so:

table tbody.yourClass td {
    padding: 10px;
}

and your HTML thusly:

<table> 
<tbody>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
<tbody class="yourClass">    
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
<tbody>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
</table>

Try that guy out :)

OLD ANSWER

whatever you do, DON'T insert blank rows...

you shouldn't have more than 1 tbody element in your table. what you can do is set the class or id attribute in your <tr> elements and give their corresponding <td> tags padding:

table {
    border-collapse: collapse;
}

tr.yourClass td {
    padding: 10px;
}

You can even assign the top and bottom <tr>'s an additional class so that they only do top or bottom padding, respectively:

tr.yourClass.topClass td {
    padding: 10px 0 0 0;
}

tr.yourClass.bottomClass td {
    padding: 0 0 10px 0;
}

and in your HTML, your <tr> tag would look like this:

<table> 
<tbody>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr class="yourClass topClass"><td>Text</td></tr>
<tr class="yourClass"><td>Text</td></tr>
<tr class="yourClass bottomClass"><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
</table>

Hope this helps!

Came across this while trying to solve it myself. I had success with putting a <br> tag right before the closing </tbody> tag. It is a purely visual fix, but seems to work on most browsers I tested.

<table>
    <tbody>
        <tr>
            <td></td>
        </tr>
        <br>
    </tbody>
    <tbody>
        <tr>
            <td></td>
        </tr>
    </tbody>
</table>

Should be accessible as well.

With credit to everyone else who answered first ...

table {
  border-collapse: collapse;
  table-layout: fixed;
  width: 50%;
}
tbody:before {
  content: "";
  display:block;
  border-top: 15px solid white;
}
tbody tr {
  border-color: #000;
  border-style: solid;
}
tbody tr:first-of-type{
  border-width: 2px 2px 0 2px;
}
tbody tr:nth-of-type(1n+2){
  border-width: 0 2px 0 2px;
}
tbody tr:last-of-type{
  border-width: 0 2px 2px 2px;
}
tbody tr:nth-child(odd) {
  background-color: #ccc;
}
tbody tr:hover {
  background-color: #eee;
}
td {
  text-align: right;
}

<table>
  <tbody>
    <tr>
      <th colspan="3">One</th>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
  </tbody>
  <tbody>
    <tr>
      <th colspan="3">Two</th>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
    </tr>
  </tbody>
</table>