Thnx for all the comments guys, makes this pain of map worth it.
@ShrannBeldworf - I can't really put up a tut as it is mostly Ascension's style, just heavily experimented with. The coast, however, was me, so here's how i did it.
Following Ascension's style, on the "land" layer add an outer glow of papyrus (ffe0c0) at size 11, increase or decrease as you see fit. This is the sandy beach and is only really noticeable when you really zoom in so feel free to leave it out.
The get the lighting effect on the water, add a new layer on top of the "ocean copy" layer but under the "shelf" layer. Ctrl-click the shelf and expand the selection by 100 pixels, feather the selection by 50 pixels and fill the selection with white. Now as any selection can only be expanded by a maximum of 100 pixels, Ctrl-click the shelf layer again and expand by 100 pixels three times so we have selection of 300 pixels out from the coast, save this selection. Feather the selection by 50 pixels and go select inverse, fill the selection with 25% gray. Load the saved selection and expand by another two lots of 100 pixels so that selection is now 500 pixels from the coast. Again feather by again 50 pixels and inverse the selection, fill with 50% grey. Next, add a gaussian blur of 200 pixels, this'll blend all of the colours into each other and make the transition form shallow to deep water smoother. Finally change the layer style to overlay so that the ocean layers underneath will show through.
If you want to you can keep expanding the slections, adding 75% grey at 700 pixels out and finally black at 900% pixels. These sizes are great for continental maps, feel free to expand or decrease the sizes for world maps and regional maps respectively. The formula is simple for this technique, the selections are coloured at equal intervals, the feather on the selection is always half of what the selection was expanded by, e.g. 25 feather for a 50 expansion, and the final blur is always double of what the expansion was.
As always, feel free to experiment until you find something that suits you. Hope people find this useful.