Bukkit

2011-12-18 16:15:08 [INFO] Running latest version of SATools.
2011-12-18 16:15:08 [INFO] 1.1
2011-12-18 16:15:08 [SEVERE] Error occurred while enabling SATools v1.1 (Is it up to date?):
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
    at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:197)
    at java.awt.Window.<init>(Window.java:534)
    at java.awt.Frame.<init>(Frame.java:420)
    at java.awt.Frame.<init>(Frame.java:385)
    at javax.swing.JFrame.<init>(JFrame.java:174)
    at onethatwalks.satools.SAToolsGUI.<init>(SAToolsGUI.java:158)
    at onethatwalks.satools.SATools.onEnable(SATools.java:182)
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:188)
    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:968)
    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:280)
    at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:186)
    at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:169)
    at net.minecraft.server.MinecraftServer.t(MinecraftServer.java:348)
    at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:335)
    at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:165)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:399)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:457)

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2nd error

2011-12-18 16:15:14 [SEVERE] Could not pass event PLAYER_JOIN to SATools
java.lang.NullPointerException
    at onethatwalks.listeners.SAToolsPlayerListener.onPlayerJoin(SAToolsPlayerListener.java:30)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:265)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:58)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:339)
    at net.minecraft.server.ServerConfigurationManager.c(ServerConfigurationManager.java:129)
    at net.minecraft.server.NetLoginHandler.b(NetLoginHandler.java:113)
    at net.minecraft.server.NetLoginHandler.a(NetLoginHandler.java:39)
    at net.minecraft.server.NetworkListenThread.a(SourceFile:94)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:527)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:425)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:457)

The first error is kind of weird. If you are running a graphical OS then this should happen, otherwise make sure that your OS configuration is set up properly. SATools will work on any graphical capable OS with Java installed. It currently does not support remote access.

For the second error I would like to know how you got that error, so that I may replicate it.