In rebuttal to Geshan Manandhar's "must have" list, I propose these modules. I prefer to think of this more as a "must consider" list though.

1. FAQ - Many sites include a "Frequently Asked Questions" page; this moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. manages the list for you, so all you have to concentrate on is the content. If you want to add an "Ask the Expert" (or advice) "column." you can add the Faq_Ask moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP..
2. Weblinks - Almost every siteA logically grouped set of content - also web site. has a "Links" page; this moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. manages that and allows you to have user-submitted links. It will even check the links on occasion to see if they still work.
3. Taxonomy Image - The taxonomy_image moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. allows siteA logically grouped set of content - also web site. administrators to associate images with taxonomy terms, which can then be displayed in addition to, or instead of, the printed term.
4. Glossary - This moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. scans posts for glossary terms (including synonyms). The glossary indicator is inserted after every found term, or the term itself is turned into an indicator depending on the siteA logically grouped set of content - also web site. settings. By hovering over the indicator, users may learn the definition of that term. Clicking the indicator leads the user to that term presented within the whole glossary or directly to the detailed description of the term, if available.
5. Site Documentation - This moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. display information from various places within the Drupal

   Drupal

   An open-source content management system that is used on this site and is taking over the world. environment, saving you time searching through many pages. Some of the information comes from internal arrays, some is derived from system calls, and some comes directly from the databaseA collection of data related to an application. tables.
6. Event - This is a simple moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. to keep track of events and show them to users in various calendar displays. It also provides an event API to allow other modules to store and work with date data. There is an Event Repeat moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. for repeating events. It also works well with several event-related modules (e.g. Sign Up).
7. Spam - The SpamUnsolicited email or web site postings that are undesirable, usually containing links to other sites. moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. provides numerous tools to auto-detect and deal with spamUnsolicited email or web site postings that are undesirable, usually containing links to other sites. content that is posted to your siteA logically grouped set of content - also web site.. SpamUnsolicited email or web site postings that are undesirable, usually containing links to other sites. can be automatically unpublished and/or deleted.
8. Image Attach - This moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. is part of the Image package; it allows you to easily attach image nodes to other node types.
9. Pathauto - This moduleAn add-on, or extension, to Drupal to provide additional functionality; written in PHP. automatically generates path aliases for various kinds of content (nodes, categories, users) without requiring the user to manually specify the path alias. This allows you to get aliases like /category/my-node-title.htmlHyperText Markup Language - the coding standard for a web page. instead of /node/123. The aliases are based upon a "pattern" system which the administrator can control.
10. XML Sitemap - This automatically creates a siteA logically grouped set of content - also web site. map that conforms to the sitemaps.org specification. This helps search engines keep their search results up to date.
11. User registration notification - Notifies the administrator of new user registrations. You can even get emails when someone updates their profile as well.