Every serious Drupal powered website will have add-on modules to extend the capabilities of that specific website. Here's the modules we think every site should have.
16. Gallery - Add one or more photo galleries to your website.
15. Editor (TinyMCE) - The most popular WYSIWYG editor for advanced content editing.
14. XML Sitemap - Creates an XML site map that works with Google Webmaster Tools.
12. Syndication - Module to consolidate RSS feeds on to a single page.
11. Meta Tags - Allows adding keywords and description to be search engine friendly.
10. Printer-friendly pages - Allows users to print just the content for each page.
9. Forward - Allows visitors to send the page to a friend.
8. Contact - Enables the use of both personal and site-wide contact forms.
7. CiviCRM - Email and manage your contacts from one place
6. Path Access - Grant or restrict access to any pages (paths) by user (role).
5. Search - Enables site-wide keyword searching.
4. Taxonomy - Categorize content with tags you name.
3. Excerpt - Allows users to manually control the teaser for a story or blog post.
2. Fileshare - The Fileshare module is used to create pages that allow browsing, uploading, downloading and deleting files from the server.
1. Google Maps. Bonus: For ecommerce capabilities, you will need the Paypal Module called lm_paypal.