Hi La Parka,
I think you just answered yourself. 🙂 But what you would do is create a form that would submit the data into a database. Have a field called 'status.' When the value is 0, that means the rebate hasn't been received. And when it is 1, that means you recieve it.
So a sample form would look like this:
<form action="myform.php" method="post">
<input type="text" name="rebatename">
<input type="text" name="datesent">
<select name="status">
<option value="0">In The Mail</option>
<option value="1">Received</option>
</select>
<input type="submit" name="sendrebate" value="Send Rebate Data">
</form>
When you submit this data, send it to a database. And then for the other half of your project, you can write an interface to update the database. That way, when you receive your rebates, you can go ahead and update it also. 🙂