I don't think any of them do.
However, that typically doesn't matter. So long as you put an LGA775 Core 2 Duo processor in the board, it should boot just fine. The "problem" will be that it doesn't detect the FSB or voltage correctly, which ultimately doesn't matter because you can change it on your own anyway.
So, don't worry about the lack of spare processor. Just buy your favorite P35 board, slap in your E8x00 or Q9x00, flash it up (even if you want to) and enjoy life.