No-one has mentioned these so far but they rock!
Pulau Weh is a small island of northern tip of Sumatra (Indonesia). Just the most fantastic place to see pelagics, You name it and it's there. Sharks, mantas, eagle rays, whale sharks, huge schools of barracuda, jacks, tuna. Mangificant wall dives and some really good deep wrecks. Excellent vis of 30m minumum.
The only downside is that to get there you have to go through some very very strict muslim areas that have up until recently been subject to civil unrest, however having just come through that area a few weeks ago things are very quite and diving is excellent.
The island is fairly small and has small beaches, but the people are just so friendly, a really sociable island.
The diving is very cheap at $24 per dive if you have your own kit and i was paying just $5 per dive for shore diving (from which it is vbery easy to see the mantas).
The other place that springs to mind is the Perhentian Islands off the east coast of mainland Malaysia. Again a small island (well two actually but make sure you go to the smaller one). The diving is very varied, some really superb corals, pinnacle dives and coral gardens. There are reef sharks, white tips, loads of morays, and the very occasional whale shark. This area is renown for it's trigger fish (so beware). The island is again very sociable and has a large number of dive shops (of which Turtle Bay Divers is by far the best).
And to please the good lady Kuala Lumpur is a really good place to visit as is Khota Baru (great night markets).
