Also digitial pictures, read the exif date/time data to reconstruct some old entries.
If your calendar supports any kind of command line scripting then you could easily rebuild entries from that data. I'm using the attachment field in korganizers calendar entries to link to the pictures. I can't wait until consumer cameras get GPS data included then the location information can be added to the journal in the same manner. I'm still looking for that perfect pim type of app than can combine more data types than just todo's, meetings, and journals, I want my pictures incorporated as well as web browser history, document editing history, etc. then I can more accuratly tell how much time I spend doing things.
Then I worte a quick hotplug script which copies my calendar to my USB flash drive every time I plug it in so I have my journal with me always.