diff --git a/include/osg/ApplicationUsage b/include/osg/ApplicationUsage
index 65fb6b46d..5276ac6fa 100644
--- a/include/osg/ApplicationUsage
+++ b/include/osg/ApplicationUsage
@@ -55,26 +55,30 @@ class SG_EXPORT ApplicationUsage
         const std::string& getCommandLineUsage() const { return _commandLineUsage; }
 
 
-        void addCommandLineOption(const std::string& option,const std::string& explanation);
+        void addCommandLineOption(const std::string& option,const std::string& explanation, const std::string &defaultValue = "");
         
         const UsageMap& getCommandLineOptions() const { return _commandLineOptions; }
 
+        const UsageMap& getCommandLineOptionsDefaults() const { return _commandLineOptionsDefaults; }
 
-        void addEnvironmentalVariable(const std::string& option,const std::string& explanation);
+
+        void addEnvironmentalVariable(const std::string& option,const std::string& explanation, const std::string& defaultValue = "");
         
         const UsageMap& getEnvironmentalVariables() const { return _environmentalVariables; }
 
+        const UsageMap& getEnvironmentalVariablesDefaults() const { return _environmentalVariablesDefaults; }
+
 
         void addKeyboardMouseBinding(const std::string& option,const std::string& explanation);
 
         const UsageMap& getKeyboardMouseBindings() const { return _keyboardMouse; }
 
 
-        void getFormatedString(std::string& str, const UsageMap& um,unsigned int widthOfOutput=80);
+        void getFormattedString(std::string& str, const UsageMap& um,unsigned int widthOfOutput=80,bool showDefaults=false,const UsageMap& ud=UsageMap());
 
-        void write(std::ostream& output,const UsageMap& um,unsigned int widthOfOutput=80);
+        void write(std::ostream& output,const UsageMap& um,unsigned int widthOfOutput=80,bool showDefaults=false,const UsageMap& ud=UsageMap());
         
-        void write(std::ostream& output,unsigned int type=COMMAND_LINE_OPTION|ENVIRONMENTAL_VARIABLE|KEYBOARD_MOUSE_BINDING, unsigned int widthOfOutput=80);
+        void write(std::ostream& output,unsigned int type=COMMAND_LINE_OPTION|ENVIRONMENTAL_VARIABLE|KEYBOARD_MOUSE_BINDING, unsigned int widthOfOutput=80,bool showDefaults=false);
 
     protected:
     
@@ -84,6 +88,8 @@ class SG_EXPORT ApplicationUsage
         UsageMap    _commandLineOptions;
         UsageMap    _environmentalVariables;
         UsageMap    _keyboardMouse;
+        UsageMap    _environmentalVariablesDefaults;
+        UsageMap    _commandLineOptionsDefaults;
         
 };
 
diff --git a/src/osg/ApplicationUsage.cpp b/src/osg/ApplicationUsage.cpp
index 795b742fa..86a75a5ae 100644
--- a/src/osg/ApplicationUsage.cpp
+++ b/src/osg/ApplicationUsage.cpp
@@ -30,14 +30,16 @@ void ApplicationUsage::addUsageExplanation(Type type,const std::string& option,c
     }
 }
 
-void ApplicationUsage::addCommandLineOption(const std::string& option,const std::string& explanation)
+void ApplicationUsage::addCommandLineOption(const std::string& option,const std::string& explanation,const std::string& defaultValue)
 {
     _commandLineOptions[option]=explanation;
+    _commandLineOptionsDefaults[option]=defaultValue;
 }
 
-void ApplicationUsage::addEnvironmentalVariable(const std::string& option,const std::string& explanation)
+void ApplicationUsage::addEnvironmentalVariable(const std::string& option,const std::string& explanation, const std::string& defaultValue)
 {
     _environmentalVariables[option]=explanation;
+    _environmentalVariablesDefaults[option]=defaultValue;
 }
 
 void ApplicationUsage::addKeyboardMouseBinding(const std::string& option,const std::string& explanation)
@@ -45,7 +47,7 @@ void ApplicationUsage::addKeyboardMouseBinding(const std::string& option,const s
     _keyboardMouse[option]=explanation;
 }
 
-void ApplicationUsage::getFormatedString(std::string& str, const UsageMap& um,unsigned int widthOfOutput)
+void ApplicationUsage::getFormattedString(std::string& str, const UsageMap& um,unsigned int widthOfOutput,bool showDefaults,const UsageMap& ud)
 {
 
     unsigned int maxNumCharsInOptions = 0;
@@ -59,7 +61,13 @@ void ApplicationUsage::getFormatedString(std::string& str, const UsageMap& um,un
     
     unsigned int fullWidth = widthOfOutput;
     unsigned int optionPos = 2;
-    unsigned int explanationPos = 2+maxNumCharsInOptions+2;
+    unsigned int explanationPos = optionPos+maxNumCharsInOptions+2;
+    unsigned int defaultPos = 0;
+    if (showDefaults)
+    {
+        defaultPos = explanationPos;
+        explanationPos = optionPos+8;
+    }
     unsigned int explanationWidth = fullWidth-explanationPos;
 
     std::string line;
@@ -70,6 +78,24 @@ void ApplicationUsage::getFormatedString(std::string& str, const UsageMap& um,un
     {
         line.assign(fullWidth,' ');
         line.replace(optionPos,citr->first.length(),citr->first);
+
+        if (showDefaults)
+        {
+            UsageMap::const_iterator ditr = ud.find(citr->first);
+            if (ditr != ud.end())
+            {
+                line.replace(defaultPos, std::string::npos, "");
+                if (ditr->second != "")
+                {
+                    line += "[";
+                    line += ditr->second;
+                    line += "]";
+                }
+                str += line;
+                str += "\n";
+                line.assign(fullWidth,' ');
+            }
+        }
         
         const std::string& explanation = citr->second;
         std::string::size_type pos = 0;
@@ -141,14 +167,14 @@ void ApplicationUsage::getFormatedString(std::string& str, const UsageMap& um,un
     }
 }
 
-void ApplicationUsage::write(std::ostream& output, const ApplicationUsage::UsageMap& um,unsigned int widthOfOutput)
+void ApplicationUsage::write(std::ostream& output, const ApplicationUsage::UsageMap& um,unsigned int widthOfOutput,bool showDefaults,const ApplicationUsage::UsageMap& ud)
 {
     std::string str;
-    getFormatedString(str, um, widthOfOutput);
+    getFormattedString(str, um, widthOfOutput, showDefaults, ud);
     output << str << std::endl;
 }
 
-void ApplicationUsage::write(std::ostream& output, unsigned int type, unsigned int widthOfOutput)
+void ApplicationUsage::write(std::ostream& output, unsigned int type, unsigned int widthOfOutput, bool showDefaults)
 {
 
     output << "Usage: "<<getCommandLineUsage()<<std::endl;
@@ -156,16 +182,20 @@ void ApplicationUsage::write(std::ostream& output, unsigned int type, unsigned i
     if ((type&COMMAND_LINE_OPTION) && !getCommandLineOptions().empty())
     {
         if (needspace) output << std::endl;
-        output << "Options:"<<std::endl;
-        write(output,getCommandLineOptions(),widthOfOutput);
+        output << "Options";
+        if (showDefaults) output << " [and default value]";
+        output << ":"<<std::endl;
+        write(output,getCommandLineOptions(),widthOfOutput,showDefaults,getCommandLineOptionsDefaults());
         needspace = true;
     }
     
     if ((type&ENVIRONMENTAL_VARIABLE) && !getEnvironmentalVariables().empty())
     {
         if (needspace) output << std::endl;
-        output << "Environmental Variables:"<<std::endl;
-        write(output,getEnvironmentalVariables(),widthOfOutput);
+        output << "Environmental Variables";
+        if (showDefaults) output << " [and default value]";
+        output << ":"<<std::endl;
+        write(output,getEnvironmentalVariables(),widthOfOutput,showDefaults,getEnvironmentalVariablesDefaults());
         needspace = true;
     }