Lou, you will probably get lots of ideas.  This one is much bigger than you 
will need, but it is accessible, free, and works.
you and your wife both install dropbox from
http://www.dropbox.com
Then you share a folder, and put your to do list in there.  Each of you see 
it, and when one person updates it, it is automatically updated where ever 
that folder is shared.
Computers, smart phones, etc.  I have no idea if it can be put on a note 
taker, because I don't know if their is a windows mobile version of the 
software.
You can share up to 2 gigs of space with other people.