The purpose of the weekly/daily agenda is to act like a page of a paper agenda, showing all the tasks for the current week or day.
Emacs contains the calendar and diary by Edward M. Reingold. Org-mode understands the syntax of the diary and allows you to use diary sexp entries directly in Org files:
* Birthdays and similar stuff
#+CATEGORY: Holiday
%%(org-calendar-holiday) ; special function for holiday names
#+CATEGORY: Ann
%%(diary-anniversary 5 14 1956)1 Arthur Dent is %d years old
%%(diary-anniversary 10 2 1869) Mahatma Gandhi would be %d years old
Org can interact with Emacs appointments notification facility. To add all
the appointments of your agenda files, use the command
org-agenda-to-appt. See the docstring for details.
[1] Note that the order of the arguments (month, day, year) depends on the setting of calendar-date-style.