Sorry, I've spent several days digging, but I can't come up with it.  I'm probably missing something simple.

I have a Visualforce page that allows users to select their list of available Account views, then displays the accounts in that view.  I am displaying the list in a dataTable instead of a dataList, but otherwise it is just as described in the developer guide:

http://www.salesforce.com/us/developer/docs/pages/Content/pages_controller_sosc_list_views.htm

<apex:page standardController="Account" recordSetvar="accounts">
  <apex:pageBlock title="Viewing Accounts">
  <apex:form id="theForm">
    <apex:panelGrid columns="2">
      <apex:outputLabel value="View:"/>
      <apex:selectList value="{!filterId}" size="1">
        <apex:actionSupport event="onchange" rerender="list"/>
        <apex:selectOptions value="{!listviewoptions}"/>
      </apex:selectList>
    </apex:panelGrid>
    <apex:pageBlockSection >
      <apex:dataList var="a" value="{!accounts}" id="list">
        {!a.name}
      </apex:dataList>
    </apex:pageBlockSection>
  </apex:form> 
  </apex:pageBlock>
</apex:page>

This page is associated with the standard account controller and the <apex:selectlist> component is populated by {!listviewoptions}, which evaluates to the list views the user can see. When the user chooses a value from the drop-down list, it is bound to the filterId property for the controller. When the filterId is changed, the records available to the page changes, so, when the <apex:datalist> is updated, that value is used to update the list of records available to the page.

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But, I don't want to just display all the Accounts in the view.  I want to collect the records from that view and manipulate them in a controller extension.  Specifically, I want to gather them, add them to a list, then use SOQL to exclude some that are also part of a different list.  Then, I will use a dataTable to display the results of my final query.

I just can't figure out how to reference the Accounts in the selected view from the custom controller extension.  I know that on my Visualforce page, they are available as {!accounts}.  But, how do I pass that set of records or IDs from the selected view to my custom controller and gather them in a list?  Can anyone give me an example of the correct syntax to reference them?

Sorry if this is obvious, and thanks in advance for any help!!