Now here's something a common citizen can do to help - all you photo developers out there, if you see pictures of buildings - and some Middle easterner "swarthy guys" in the pics - bet they had to look like tourists and include themselves in the pics...all those should be noted, extra copies made of the pics and kept in a file...if one of the buildings goes boom - pull out that file and you've got a pic of the perp!
Could also alert authorities of interest in buildings.