Here's what I keep:
Bank Account #s, Bank phones
Contacts list and PLAN of Contact with
Evacuation - rendevous Plans
Credit card account and cust. svc. #s
Driv. Lic / Passports
Home inventory/Photos in 5mpix. resolution
(I've confirmed that I can zoom in on all serial #s)
Insurance documents & Ins. Co. Phone #s
Investment account numbers
Titles and Deeds
Wills and Durable/Healthcare Power of Attorney

I do not worry about the data format, because I think these need to be updated frequently anyway. I use .pdf for documents and .jpeg for the photos. I have verified they are viewable and printable on multiple platforms, and I doubt that these formats will become obsolete without my knowledge (and plenty of time to change formats).

They are encrypted using a symetrical public key program, and anyone I would want to be able to access them can. Storage is as follows:
One set burned to DVD and sent to a family member out of town. One set burned to a DVD and stored in my cache. One set is uploaded to my internet email account.

And I feel paranoid doing all that!