It might be worth setting up a Neighbourhood Watch Group in your area.
At least you'll be able to circulate news of suspicious activity quickly and easily to the members (and the local PCSO's who respond as soon as possible). Of course, there's always 999 if it's an emergency and 101 for a non emergency.
Being in a NWG doesn't stop the suspicious activity but it makes members a little more safety/security conscious.
You've probably seen my posting in the 'Attempted break-ins, Woodville Drive area' topic regarding setting up a group and as mentioned - it's easy to manage.
So, not only would you have the 'excellent' Marple Website to circulate any info on but you would also have the support of the local police.