Yes - it's very simple:
contacts.txt - in order of surname, firstname
Surname, FirstName, Primary telephone number with code, Email address so:
Joe, Bloggs, 02033345545, joe@bloggs.com
I only keep a single number for people, but you could extend it to two numbers if you want.cal.txt - latest dates at top of file:
2012/02/02 16:00+ What to do # time specific event
2012/03/03 --:-- Someone's birthday # all day event
When something is done, the line is deleted. If something is not done on the date, it is just left as "overdue" at the top.