I do alot of data visualization these days and heatmaps are often a big part of that. I couldn't find any good presets, so I decided to create my own. Hope you like them.
1) Double click the grd file to load the gradients into your presets.
2) Select the brush tool, with the following settings: https://www.evernote.com/shard/s54/sh/ac318aad-12ba-46dc-8b94-d9cc94d16222/7a467380e02ad5b5/res/44bb2462-bb38-44d8-810f-9760789868ae/skitch.png
3) Make sure your layer style has this setting: https://www.evernote.com/shard/s54/sh/426c6f98-0e67-43e3-b505-0ddd277ccb61/dfda6cd3a7338aac/res/2a554528-d30c-42c5-a390-cca1396a0c8e/skitch.png
4) Start drawing!
Use the example PSD file to get started, if you can't figure it out.