Drupal Book: Acquia Modules

Page layout: Panels 2
Custom content: CCK, Date, Imagefield, File
Views: Views 2
Lightweight markup: Marksmarty
WYSIWYG: Kupu (Discuss WYSIWYG editors here)
Scheduled publishing: Workflow, Actions
Image management: As fields - Imagefield, Imagecache; As nodes - Image, Image assist
Events: Calendar
Forums: Forum
Comment spam filter: Mollom
Social bookmarks: TBD
Content rating: Voting API, Fivestar
Search: in core, ApacheSolr
Categorization: in core
RSS: in core
Content aggregation: tbd
Workflow: Workflow
Content versioning: Core, Diff
Tag clouds: Tagadelic
SEO URLs: Pathauto
Utilities: Primary Tag, Custom pager, JS Tools, Google Maps, Google Analytics, Wiki freelinks
Import / migration: tbd
Authentication: Persistent login, Securesite, LDAP, OpenID
User Groups: Organic groups
Email gateway: tbd
Email notification: Subscriptions