Thanks for the suggestion!  I've modified the code to use the <apex:selectList> and added a command button.  However,  I was wondering if its possible to rerender the detail outputPanel with onchange event of selectList, without using the button..  Here's my code:

VF:

<apex:page controller="contactController" showHeader="true" tabStyle="Contact">

     <apex:form >

        <apex:selectList id="chooseColor" value="{!string}" size="1" >
            <apex:selectOption itemValue="detail" itemLabel="Detail"/>
            <apex:selectOption itemValue="history" itemLabel="History"/>
            <apex:selectOption itemValue="opentasks" itemLabel="Open Activities"/>
        </apex:selectList> 
        
      <apex:commandButton value="Test" action="{!test}" rerender="out" status="status,detail"/>        
        
     <apex:outputPanel id="out">
        <apex:actionstatus id="status" startText="testing...">
            <apex:facet name="stop">
                <apex:outputPanel >
                    <p>You have selected:</p>
                    {!string}
                </apex:outputPanel>
            </apex:facet>
        </apex:actionstatus>
     </apex:outputPanel>                
                        
    <apex:dataTable value="{!contacts}" var="c" cellpadding="4" border="1">
      <apex:column >
        <apex:facet name="header"><b>Name</b></apex:facet>
        
        <apex:commandLink reRender="detail">{!c.name}
          <apex:param name="id" value="{!c.id}"/>
        </apex:commandLink>
      </apex:column>
      
      <apex:column >
        <apex:facet name="header"><b>Account Name</b></apex:facet>
        {!c.account.name}
      </apex:column>
    </apex:dataTable>

</apex:form>  
  
  <apex:outputPanel id="detail" >
    <apex:detail subject="{!contact}" title="false" relatedList="false" rendered="{!string == 'detail'}" />
    
    <apex:relatedList list="ActivityHistories"  subject="{!contact}" rendered="{!string == 'history'}"/>
    
    <apex:relatedList list="OpenActivities"  subject="{!contact}" rendered="{!string == 'opentasks'}"/>
    
  </apex:outputPanel>
  


</apex:page>

Controller:

public class contactController {

    String s = 'detail';

    public String getString() {
        return s;
    }

    public void setString(String s) {
        this.s = s;
    }

    public PageReference test() {
            return null;
        }
   
   public List<Contact> getContacts() {
      return [SELECT Id, Name, Account.Name, Phone, Email
              FROM Contact
              ORDER BY LastModifiedDate DESC LIMIT 10];
   }

   public Contact getContact() {
      Id id = System.currentPageReference().getParameters().get('id');
      return id == null ? new Contact() : [SELECT Id, Name
                                             FROM Contact
                                            WHERE Id = :id];
   }
}