Hai Swamy,

   I have solution for your problem, which is  using salesforce schema and describe methods.

  See how nice salesforce is handling all these metadata information!!!.

  Below is the attched Visualforce Markup and Apex code.

 Please modify accordingly as per your requirement.

<apex:page controller="objectController">
    <apex:form>
         <apex:selectList  value="{!object_Name}" size="1">
          <apex:selectOptions  value="{!options_Objects}"/>
              <apex:actionSupport  action="{!childList}"  event="onchange"/>
         </apex:selectList>
         <apex:selectList   >
              <apex:selectOptions  value="{!options_Childs}"/>
         </apex:selectList>
    </apex:form> 
</apex:page>

public class objectController
{
 
  Public  List<SelectOption> options_Objects {get;set;}
  Public  List<SelectOption> options_Childs  {get;set;}
  Public  String object_Name{get;set;} 
  
  public  objectController()
  {
       options_Objects  =   new  List<SelectOption>();
       options_Childs   =   new  List<SelectOption>();
       List<Schema.SObjectType> GlobalDescribe     = Schema.getGlobalDescribe().Values();
       for( Schema.SObjectType ObjectType :GlobalDescribe)
       {
        options_Objects.add( new SelectOption( ObjectType.getDescribe().getLocalName() ,  ObjectType.getDescribe().getLabel() ) );  
       } 
   } 
   public void childList()
   { 
        options_Childs.clear();
        Schema.DescribeSObjectResult R =  Schema.getGlobalDescribe().get( object_Name).getDescribe();
        for( Schema.ChildRelationship  Child: R.getChildRelationships())
        {
         options_Childs.add( new SelectOption( Child.getChildSObject().getDescribe().getLocalName() ,  Child.getChildSObject().getDescribe().getLabel()  ) );  
        }
     
   }




}

 Please have a look and feel free for further clarifications..

Thanks.

Shebin,

KVP Business Solutions,

Bangalore.