Some community subreddits of interest:
http://www.reddit.com/r/space
http://www.reddit.com/r/tothemoon
http://www.reddit.com/r/SpaceCenter/
There's organisations:
CStart (New): http://www.reddit.com/r/space/comments/id7i4/hi_rspace_if_there_was_an_open_source_space/
Open Space Movement: http://www.reddit.com/r/space/comments/ere01/space_needs_people/
Copenhagen Suborbitals - Open Source and Non Profit space. Video of their latest launch: http://www.youtube.com/watch?v=GmGmymAWI4E Main site: http://www.copenhagensuborbitals.com/
Project Icarus, interstellar travel: http://www.icarusinterstellar.org/ (They have charity status: http://www.tauzero.aero/)
Other: Someone asked how to get involved with a space program: http://www.reddit.com/r/space/comments/fdhex/how_does_one_get_involved_with_the_space_program/
Hint: Make sure you're able to take the work you've done with them to another open space organisation if you prefer!
I quickly collected this information because a lot of people were concerned (to the point of being disillusioned) with the Space Shuttle being discontinued. I hope it will at least point space-passionate people in the right direction. If you have any information to add for others interested in space, please post!
Final note: Enjoy this video, The Future of Space: https://www.youtube.com/watch?v=7CObXMEGzmY