I think this would be a great idea! Most ex-pats are used to using the internet to source and access a range of services and service providers; the 'shopping online' thing is second nature to us. However, here it's not - and this was a real frustration to me when I first got here! NO BUSINESSES seem to have a website - and if they do, they are not updated and maintained, even the government ones!! (Case in point: have you tried looking at the Brunei Tourism website? Still has LAST YEAR's calendar of events up. And the BruHomes website - the place to look for properties to buy/rent - has listings on there dating back to 2008!!!)
I ended up discovering many of the products and services I needed either by accident - by simply wandering around commercial areas to see what was what - or by word of mouth, from colleagues and other locals.
Brunei seems to still see itself as one big 'kampong' - and to that end, the old 'word of mouth' means of doing business and advertising your services is still viewed as the best way, it seems, by many businesses. They just don't bother to advertise themselves or make their products/services available online, because they assume their customers won't seek for them that way - and, where the local population is concerned, they may be right.
But the ex-pat community don't opertae that way: they WOULD like some sort of online directory, definitely. What you'd have to do is convince the local businesses that it's in their ineterests to go down this route! 