Yesterday I upgraded my site to Community Server 2.1 RTM. I'm astonished how many additional mods I'm already using:
Community Server MVP's Alabaster CSModule Package
A collection of CSModules written by CS MVPs and myself. (I contributed the Akismet spam rule btw)
Provides a secure RSS feed for all comments within a certain blog. It also provides information like if it is an actual comment or a trackback, the post's name, URL, if it is approved, and then it gives quick links to approve/disapprove, view, or delete the comment.
A Lightbox module for any photo from the gallery, an URL or Flickr.
Improved version of Scott's Flickr for Community Server
Add a Flickr area to the content selector, which enables you to select images from your Flickr account.
This module allows you to easily map one URL within Community Server to another. I for instance use it to map both my blog and my gallery to the root.
Syntax Highlighting module
Formats code snippets with syntax highlighting. I cannot give you any link, because I'm using a modified version of a CS1.1 module, and I don't know the original author anymore.
CommunityServer OpenSearch Handler
Adds OpenSearch support to your blog, allowing IE7 users to search your site from their toolbar without any installation.
Tracks your comments across the blogosphere.
I just noticed that three and a half modules of the modules are written by Ken Robertson. Seems as he is the most active guy on the Community Server community. [;)]