If you want forum boards, here a list I've pulled out of my Favorite Places:
http://www.shatters.net/forum/viewfo...b2ec77d875c105
This "Physics and Astronomy" forum is a sub-forum of the Celestia forum
http://www.orbitersim.com/Forum/defa...x?g=topics&f=2
This "Space maths & physics forum" is a subforum of the Orbiter Space Flight Simulator forum.
http://www.physicsforums.com/forumdisplay.php?f=2
Nereid already mentioned this one. This "Astronomy & Cosmology" forum is a subforum on Physics Forums.
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl
This is my forum on gravitysimulator.com
http://www.abovetopsecret.com/forum/89/pg1/srtpages
This "Space Exploration Discussion Forum" seems to have an ATM theme to it.
http://www.artofproblemsolving.com/Forum/index.php?f=8
"Art of Problem Solving Forum"
http://www.braeunig.us/space/
"Rocket and Space Technology forum". This is Bob B's site.
http://www.scienceforums.net/forum/f...splay.php?f=15
"Astronomy and Cosmology - Science Forums"
http://www.clannad.net/forums/index.php
"Extrasolar Visions"
http://forums.seds.org/
SEDS forums
http://www.unmannedspaceflight.com/index.php?act=idx
Unmanned Spaceflight forum
http://www.mathhelpforum.com/math-help/
Math Help Forum
http://207.111.201.70/php/forum.php
Systemic Forum, dedicated to using their software console to find planets hidden in radial velocity data.
http://astro.forumup.co.uk/?mforum=astro
Astro Chat