This will work for Leads. It gets content for a Salesforce page that shows most recent leads and extracts the Ids from there. These are then put in a list and used to query the Lead object.

This can be adapted for other objects by changing the lktp parameter to the prefix of the object you want to lookup and the lknm parameter from CampaignMember to an object name that has a lookup field to that object. You also have to change the findstring parameter.

public with sharing class ReferralsAndLeadsTabController {

    //public List<Lead> mruLeads{get;set;}
    public List<Lead> mruLeadList{get;set;}
    private void setMRULeads(){
        // Salesforce does not give us the most recent leads so this work around will suffice
        // We get the content of a Salesforce page that displays the Recent leads and then
        // extract the most recent ids from there.
       
        // This url is lookup page for field lookup up Lead object
        String url = '/00Q/o?nooverride=1';
        PageReference pageRef = new PageReference(url);
       
        String lookupContents = pageRef.getContent().toString();
        String findString = '\'00Q'; // Lead prefix
        integer leadIdIndex = lookupContents.indexOf(findString) + 1;
        List<Id> leadIdList = new List<Id>();
        String prevLeadId = '';
        while(leadIdIndex > 0){
            String leadId = lookupContents.substring(leadIdIndex, leadIdIndex + 15);
            if(leadId <> prevLeadId){
                leadIdList.add(leadId);
                prevLeadId = leadId;
            }
            leadIdIndex = lookupContents.indexOf(findString, leadIdIndex + 15) + 1;
        }
        system.debug('LeadIdList = ' + leadIdList);
        Map<Id, Lead> mruLeadMap = new Map<Id, Lead>([SELECT Id, Name, Company
                                                        FROM Lead
                                                        WHERE Id in :leadIdList]);
        // Now loop thru the ids and build the list with the leads in the correct order
        mruLeadList = new List<Lead>();
        integer seqnum = 0;
        for(Id leadId : leadIdList){
            mruLeadList.add(mruLeadMap.get(leadId));
        }                                                       
    }
    public ReferralsAndLeadsTabController(ApexPages.StandardSetController stdController) {
        setMRULeads();
    }
}