This is a good idea and would make Kareha-boards much smoother to read.
I've used bbs2chreader for some time now, and it shouldn't be to hard to create something like that for browsing Kareha-boards.
Actually, I think we Anonymous users should be able to do some work ourselves. I've thought about modifying bbs2chreader to work with Kareha, but since I know absolutely nothing about making Firefox-plugins, it hasn't progressed at all.
I love love the idea of gathering a team of programmers and create applications for use with Kareha.