UPDATE: in August/September 2014 I had a four-day stopover in Singapore en route back from my long South-East-Asia trip. I went to Changi on a tour and also discovered quite a few extra sites on my own. A full report and extra chapters will follow, once I've found the time to write it all up. First a number of other places still have priority, so please bear with me. 
A micro-state on an island at the southern tip of Malaysia. Now an independent city state, it used to be a British colony and military stronghold in South East Asia. In WWII it was conquered and occupied by Japan. And that's the dark connection.
There are numerous WWII-related sights, more of interest to the war tourist, although the underground bunker complex of the Fort Canning Battle Box may also qualify as dark tourism proper. (For more info see Chuck Thompson's book "The 25 Best World War II Sites – Pacific Theater")
But it's manly for one particularly infamous site that Singapore has to feature on these pages: Changi prison, where POWs were incarcerated during the Japanese occupation and often sent to perform forced labour elsewhere (e.g. on the Death Railway in Thailand).
Singapore is a famously modern and squeaky clean place that is well developed for tourism – but imposes an unparalleled plethora of restrictions/bans, so an astute awareness of this and generally restrained behaviour are required when going there.
Many visitors come for just a day or two as a stopover en route to places further away (e.g. Australia, New Zealand or Indonesia). And while ther are several sites relevant to dark tourism and worth travelling to in their own right, it probably makes sense for the dark tourist too to use Singapore as a kind of springboard to other destinations in South East Asia and beyond, including, right next door, Malaysia and, a bit further afield, East Timor.

©, Peter Hohenhaus 2010-2017