Advertisement: adsense module
Spam prevention: captcha
SEO: PathAuto, XmlSitemap
Statistic: Google Analytics
Similar content: Similarities
Content contruction kit: CCK (content) and cck_map, view, view_bonus (for additional grid view)
Feeds reader and turn feeds into nodes: FeedAPI
Rating system: Voting API, fivestar
Image gallery (building from View + View bonus + Imagefield): ImageCache, ImageField, CustomPagers. Lightbox2, jquery_update for beautiful display
Put image from gallery into any text: image, image assist || IMCE || imagepicker
Menu by image: imagemenu
Display tags clouds: tagadelic

WYSIWYG editor: TinyMCE, module TinyMCE (bugs if use with img_assist) or TinytinyMCE (easier use)

Workflow: Workflow