One of your mods is causing a memory leak and crashing the server a few seconds after it starts. I know in single player this was an issue with RedPower at one time (a few threads about it), though I'm not sure what mods are causing it here as the log just doesn't detail too much sadly
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After you created your mystcraft age did you do anything in it? Place world ancher/chunk loader/etc?
From the errors it looks like something is caching the two worlds that thaumcraft is trying to unload. Finding what is doing that is the first step. I'm pretty new (only a few months) into FTB server management though, so I couldn't tell you what mod it might be, or how to figure out truthfully...hopefully someone a lot more knowledgeable can.
Though, I would search around (forum/google/etc) using the error below and see if you can find anymore information about it and ways to solve it on a server (most of what you'll find is single player based sadly, I don't have time to weed through all of it right now). "[SEVERE] [ForgeModLoader] Detected leaking worlds in memory. There are 2 worlds that appear to be persisting. A mod is likely caching the world incorrectly"
Code:
2013-03-22 17:33:09 [INFO] [STDOUT] Loading NEI
2013-03-22 17:33:37 [INFO] [ForgeModLoader] [Thaumcraft] Removed -5 aura nodes when world 7 unloaded.
2013-03-22 17:33:38 [INFO] [ForgeModLoader] Unloading dimension 7
2013-03-22 17:33:38 [INFO] [ForgeModLoader] [Thaumcraft] Removed -5 aura nodes when world 1 unloaded.
2013-03-22 17:33:38 [INFO] [ForgeModLoader] Unloading dimension 1
2013-03-22 17:33:39 [SEVERE] [ForgeModLoader] Detected leaking worlds in memory. There are 2 worlds that appear to be persisting. A mod is likely caching the world incorrectly
2013-03-22 17:33:39 [SEVERE] [ForgeModLoader] The world 710818 (world) has leaked.
2013-03-22 17:36:23 [INFO] [Minecraft] Stopping the server