October,
I'm very sorry for this very sad situation that has been added to your already difficult life.
The letters are a very good idea--for graduations, wedding, birth of a grandchild, etc. If he still looks relatively good, maybe someone could videotape some messages from him to her. A woman I know who died way too young had purchased some small gifts for birthdays, Christmas and other important days for her children, wrapped them and attached cards. This is probably wayyyy to much for a man to consider doing and possibly not affordable, but maybe a few small, meaningful things (i.e. a charm bracelet with charms that could be added on important days) he could leave with you.
That's all I can think of for now.
((((((((October & C)))))))))))))))
Blessings,
Brigid