Automatic Archive for Photoblog?

I have a photoblog and I would like to add an archive page which displays thumbnails of the photos rather than the dates or titles (like this http://photoblog.xyloid.org/mosaic/). However, I would like for it to be automatic, instead of having to go in and create a thumbnail for every post and then add the thumbnail to a gallery page. Is there a plugin which does this. If not, any suggestions? Thanks!