Most of my more expensive equipment is marked by a product called DNA Fingerprint , you paint a small amount on maybe uderneath or inside equipment , and is invisable when it dries , in the clear liquid you paint on are whats called micro Dots all with printed serial numbers that are unique to you , when you first buy it , you call up the maker with the serial number from the products package , that number is then registered to you , If any lost or stolen items are handed , most police forces are now checking for these micro doted markings , and can check a central database as to who the micro dot serial number is registered to .
All my hi fi , tv's computer etc are all marked as well ..
getting you stuff back all depends on it ending up at a police station though !!