I've created a pretty simple script to trawl through all the files that we make public to generate a timeline. This is based on the contents of the Exif information if available, otherwise I'm afraid it simply drops back to using the last modification date for the file which isn't very clever. Of course this can also go wrong if the Exif information is wrong, but I'm pretty diligent about getting this right on my cameras.
As of 2006-01-03 I'm simply grouping the photos by month and then by folder. This works quite well for our folders, but not so well for Emma's as they are already in some sort of date order.
Obviously it really helps that I've already got all the thumbnails I need on the website. The only niggle is that it takes a while to download them all, but that's pretty unavoidable