Wetness/Glowing Shaders
A shader to make things look like they're emerged from fluid (possibly a set for different colours; water, blood, honey, chocolate and so on) and another which can be applied to something to make things glow various different colours, please!
Being able to make engine nozzles and spiritual characters look like they're literally glowing (in the same way as the glowing eyes set does) would come in very useful. Would probably help to create a convincing illusion for headlights being switched on, too.
As for wetness, we still don't have a way to mimic wakes and other movement in water, but it's especially difficult to convey the look of, say, a submarine or shark's dorsal fin looking like it's just emerged from the water without a convincing 'sheen' to it. I've experimented with upping the percentage of reflectivity in the surfaces tab, but it doesn't seem to make very much difference. Would have obvious benefits for anyone creating horror-based scenes, if they can apply a shader to make an object or figure look like they're slick with blood, too (Gore-Dom is a great product, but doesn't create a look of wetness, which can lead the viewer assuming that the blood looks more painted on than anything). And, obviously, it'd be great for making food look like it's been marinated in sauce or lips seem like they've sampled a drink.