Find table cell knowing row and column ids with jQuery

I have a simple table, where I have set IDs for headers and IDs for rows. Given an ID for both, I need to find a corresponding cell at the intersection of those two.

Example:

<table id="tablica">
    <thead>
        <th id="bla">Bla</th>
        <th id="bli">Bli</th>
        <th id="blu">Blu</th>
    </thead>
    <tbody>
        <tr id="jedan">
            <td>1</td>            
            <td>2</td>
            <td>3</td>
        </tr>
        <tr id="dva">
            <td>4</td>            
            <td>5</td>
            <td>6</td>
        </tr>
        <tr id="tri">
            <td>7</td>            
            <td>8</td>
            <td>9</td>
        </tr>
    </tbody>
</table>​​​

So if I have id="bli" and id="dva", that means I want to do something with cell having value 5 in this example.

edit: There are a lot of correct answers, I upvoted all of them, but unfortunately I can only choose one as correct.