drupal----recommend modules to learn
i want to write modules by myself very much. but for drupal and php, i am not good at them, only on the learning way of them.but i like them very much. so i am sincerely expect some seasoned drupalers or gurus can recommend some simple modules for me to research and learn.i know  CCK and views are very popular,but they are too big. it's hard to learn from it for a newbie. any tips would be appreciated.
drupal----recommend modules to learn
===

i want to write modules by myself very much. but for drupal and php, i am not good at them, only on the learning way of them.but i like them very much. so i am sincerely expect some seasoned drupalers or gurus can recommend some simple modules for me to research and learn.i know  CCK and views are very popular,but they are too big. it's hard to learn from it for a newbie. any tips would be appreciated.