Sometimes on our localbox [wamp : localhost] we found that when enabled css aggregation and javascript aggregation then we cannot able to access our admin area and user login area. I mean we cannot able to access the site because we enabled css aggregation. Now you cannot access the admin area and you cannot even login so what to do.

You have to disable your css aggregation from database using your phpmyadmin. Follow the below steps:
     1. Open phpmyadmin and select the database which is used by the drupal instance. Read more about Drupal Performance : Disable CSS Aggregation from database using phpmyadmin

Here is a list of modules you will always find useful when creating website IMO.

Enjoy Drupaling!!!

1. Views - http://drupal.org/project/usage/views
2. CCK - http://drupal.org/project/usage/cck
3. Panels - http://drupal.org/project/usage/panels
4. Pathauto - http://drupal.org/project/usage/pathauto
5. Administrator Menu - http://drupal.org/project/usage/admin_menu
6. Nice Menus - http://drupal.org/project/usage/nice_menus
7. Image Cache - http://drupal.org/project/usage/imagecache
8. Date - http://drupal.org/project/usage/date Read more about 25 Drupal Modules you must have