Merge Cells based on an adjacent row of values

I am using Excel 2007 and trying to find a macro that can automatically make a merged heading in one column based on the value in an adjacent column. I have attached a simple example of what the finished product would look like. The problem is that the number of lines for each value will keep changing, so the merged cells need to automatically expand to encompass any new entries. I have been trying to find an answer for this myself without any luck, any help would be appreciated.

No sorry. I should have mentioned that the list is populated elsewhere and sorted into the sheet I need. This is a simplified example, but I have attached what happens when I have more data added. Basically what I want is a macro that will resize the merged area if the value in the adjacent column is a specified value. Thanks again.