Harmy said:
And just FYI, the DVD9 AVCHD and large MKV are still on, but I thought a BD25 with menus and stuff would be pretty awesome too but I wouldn't have any way to burn it - and it's just an idea, I need to find out how hard it is to author BDs first.
Try multiAVCHD first -- it's the freest, simplest one out there. You can actually choose to output to BDMV if you like. You can create an XMB-style menu (like the PS3 interface), a Slide menu (iTunes like) or a Carousel menu... all work with a background image of your choosing. Each video title is represented by a thumbnail, either from a frame of the movie itself or again, your own image.