• WP Robot Extremely Autoblogs Plugin (worth $169), post content from article site, Amazon, Clickbank, Yahoo Answer to your site, you can set the time stamp for past or future posts and targeted keywords for each category.
• Uniques Content Plugin (worth $15), make your auto content more uniques in Search Engine without change the words.
• SEO Boster Pro (worth $39), Optimized the crucial structure on the site to more indexed and more traffics.
• Automated Keyword Generator, improve SEO with add meta keywords and meta description base on your title post
• Platinum SEO, optimize and add keywords targeted on every post title and description, so every post have different keywords and description than the homepage, there’s option for set no follow/do follow links in post.
• XML sitemap generator,  create a sitemap periodically to notice Search Engine about new contents on the site.
• Smart Tags, add tags automatically from post content
• WP-Super Cache, is an extremely efficient WordPress page caching system to make you site much faster and responsive.
• OnlyWire Autosubmitter, submit every nEditorew post to over 30 Social Bookmarking sites automatically.
• Sitemap Page Generator, create sitemap page for human visitor easily (I’m using this if the Theme don’t have Sitemap page template.
• Opt-in form Plugin, create catchy opt-in form for subscriber
• Contact Us Plugin, create contact form for your visitor and directing to your email
• Bookmarking Plugin, create popular Social Bookmark buttons bellow each post, this will make your visitor easily bookmark the post to their favorite bookmarking sites.
• Statusnet Plugin, can automatically post update as status at Identi.ca everytime new posts added.
• Smart 404 Plugin, redirect broken link or not found terms to specific page so the visitors not lost at Not Found page, in this case I set it redirect to Sitemap Page and the visitor will found related articles which they search for.
• Statpress Plugin, Manage Statistics about blog visits. Collect information about visitors, spiders, search keywords, feeds, browser etc. Previously I use Wassup plugin but seems heavy for the site.
• Pretty Link Plugin, using this I can redirect the affiliates links to the site’s permalinks, easy to remember and also make it like part of the site.
• No Duplicate Content Plugin, sometimes an autoblog will grab the same contents especially if we set the similar keywords. With this plugin we can manage which duplicate posts must be removed.

Read other plugins which I usually use and for some case which it must be installed.