Firstly, you may also wish to know that the flight crew are automatically absolved of responsibility in the event of pax. fatalities/injuries resulting in turbulence, even if the seat-belt signs were not illuminated.
Two reasons-turbulence occurs unpredictably; and a fatality or injury could perceivably occur in the time between the initial encounter of rough air, and the time it then takes the flightcrew to illuminate the signs.
Don't forget the crew advise pax. prior to T/O of the need to stay seated with belts on during the entire flight, as a precaution against severe CAT.
The stall of that SQ? Well, here's the extract:
16 Oct 1993 9V-??? [I wonder who supressed that info!!
"This (unknown) SQ a/c appears to have lost airspeed and stalled while at cruising altitude on a normal SIN-LHR sector: witnesses in the cabin reported buffeting and audible stall-warnings, before some of the cabin staff were thrown off their feet and pax. drinks hit the ceiling. The pilots later said that one of the airspeed indicators appeared to be displaying "frozen" readings, and was therefore disagreeing with the other: the incident occurred while they were considering which instrument was providing the correct information. Boeing (and it's suppliers) examined all the equipment, systems and software that might have had a bearing on the problem, but nothing was found. The a/c itself was undamaged, and after a thorough check was returned to service.
Hmmm, something smells fishy about that....
Anyway, here's another interesting incident, out of the many I have relished reading:
5 Apr.97 G-BNLF 
This BA a/c suffered significant damage while attempting to land at Lilongwe Airport, Malawi, during a heavy rainstorm; the GWPS sounded a "sink rate" alarm immediately before touchdown, and windshear may have played a part in the subsequent 2.85G (!!) initial impact. The aircraft bounced into the air (a 744!!) again after this first contact, and the crew initiated a GA, which was followed by a perfectly normal landing. After a full "heavy landing" inspection at Lilongw, the a/c was returned to service, and flew two more sectors before returning to LGW. Only at LGW was the extent of the damage fully realised, and the a/c withdrawn from service. After being ferried to BA's maintenence HQ at LHR, a thorough check revealed a frightening degree of damage. The repairs took 6 weeks to complete and cost several million pounds.
Lots more 744 incidents in this great book.