Split report with different column headers

Question

Hey everyone, I've done quite a bit of googling and searching on this forum, and I'm wondering if anyone has tried to do the same thing as me, and found a solution. I'm looking to make a report like this:
REPORT
GROUP-1
     SUB-GROUP1
     HEADING 1     HEADING 2
     value1          value1
     value2          value2
     value3          value3
GROUP-2
     SUB-GROUP2
          SUB-GROUP3
          HEADING 1     HEADING 2
          value1          value1
          value2          value2
          value3          value3I can write a query that gets output like that, but I'm trying to find the best way to display in at Apex.
It can be looked at in two ways, I guess. One way is a tree where the leaves have multiple columns in them, and the other is a report broken up by different headers. I would like to be able to use the features of an interactive report, but haven't been able to find a way to format it this way. I've also looked for tree plug-ins but haven't found one that's well designed for reporting, more for navigation or searching. (I've looked at DTreeTable and TreePanel ) If I can't find something that exists, then I'll look into just writing a procedure that spits out HTML.
If anyone knows of a plugin that would let me group reports this way (either free or commercial) or has run into the same requirement and found a solution, I'd be interested to know what it was.
If you need any more information, please let me know and I'll elaborate the best I can.
Thanks!

Answer 1

Thanks for the reponse Tyson.
I'm looking more for a flat reporting plugin. It doesn't have to be able to collapse and it doesn't really need navigation - it just needs the hierachrial structure. I wanted to keep the built in features of an interactive report if possible (like searching, sorting, selecting columns etc.) but if that's not available, then anything that can format output similar to my sample would be perfect.