Other blogsThere are quite a few blogs around the world, targeting specific languages. These sites are community and volunteer run. Find one you like and get involved. Often, these sites are updated more frequently than elementaryupdate.
Italy: noiaggiorniamo.blogspot.com (closing?)
Malaysia: elementaryluna.blogspot.com (English)
The Google+ Communityelementary's Google+ Community is very active, and maybe the best place to go. Whether you have a question, just want to show your desktop or sharing your ideas, the Community is ready for it. You can also find mockup's and so on there. Visit the Google+ Community.
On LaunchPadSquashing bugs for elementary is very important. So, you can submit bugs and view the status of fixes at the official LaunchPad site for elementary. LaunchPad site or check out the Beta 2 Page.
elementary on deviantARTOn the official deviantART Communites, you can find many mockup's. Discuss them or submit your own! There are the 2 groups: #elementary-os and #elementary-art. #elementaryOS Group.
Visit the #elementary-art Group.
elementary's sub-redditAre you a redditor and love elementary? Well, I think the elementary sub-reddit is the place to go for you. It's open for everything: questions and submissions of any kind. elementary sub-reddit.
elementary Apps SpreadsheetThere is a Google Docs Spreadsheet, listing many elementary-style apps. It also describes their stability. This document is free to be edited, so why not submit your own elementary App? Spreadsheet.
The social networksOf course, there are the social networks. You'll find there the least information, however.
elementary on Google+
elementary on Twitter
elementary on facebook