Autopost /Schedule plugin allows site members to add posts or blogs with future scheduled date. Post will be published on site automatically on scheduled date and time. It is a Very useful feature for new sites to look busy and active.
Sitemap is a tool that inform search engines about the structure of your site. By placing a sitemap on your website, you enable Search Engine crawlers (like Google) to find out what pages are present and which have recently changed, and to crawl your site accordingly. You don't have to manually submit sitemap as it automatically (if settings is enabled in the admincp) Notify Popular Search Engines (Google, Bing) when sitemap changes.
Badges plugin encourages members to perform various activity, frequently interact with each other and compete with friends in your social network. It is a simple and fun way to increase interaction and reward member activities. You can create different badges and define conditions to get them, for instance 30 blog posts to get Super Blogger badge and 10 music tracks for Music Lover badge. Badge can contain multiple conditions.