User:EdLoach/JOSMPostcodes

Save the content below as postcodes.xml on your local drive and add it using the Map Paint dialog in Preferences.

 <rules name="Postcode Highlighter"
      description="Highlights addressed properties with/without postcodes"
      version="0.2_2013-03-14"
      author="EdLoach"
      shortdescription="Missing Housenumber/name/Postcode highlighting">
 <rule>
   <condition k="building" v="yes"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="house"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="shop"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="hall"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>  
 <rule>
   <condition k="building" v="church"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>  
 <rule>
   <condition k="building" v="police_station"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="bar"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="hospital"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="doctors"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="hotel"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>  
 <rule>
   <condition k="building" v="guest_house"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="nursing_home"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="building" v="office"/>
   <area colour="house#ff6600A0" priority="-10000"/>
 </rule>
 <rule>
   <condition k="addr:housenumber"/>
   <area colour="numberedhouse#f807f8A0" priority="-9500"/>
 </rule>  
 <rule>
   <condition k="addr:housename"/>
   <area colour="numberedhouse#f807f8A0" priority="-9500"/>
 </rule>
 <rule>
   <condition k="addr:housenumber"/>
   <condition k="addr:postcode"/>
   <area colour="postcodedhouse#00da8bA0" priority="-9000"/>
 </rule>
 <rule>
   <condition k="addr:housename"/>
   <condition k="addr:postcode"/>
   <area colour="postcodedhouse#00da8bA0" priority="-9000"/>
 </rule>
 </rules>