A space-separated list of HTML tags allowed in the content of feed items. (Tags in this list are not removed by Drupal.)
Number of feed items displayed in feed and category summary pages.
The length of time to retain feed items before discarding. (Requires a correctly configured cron maintenance task.)
The type of category selection widget displayed on categorization pages. (For a small number of categories, checkboxes are easier to use, while a multiple selector work well with large numbers of categories.)