ZLTweaks

Release 8:

Grass top and side overlay has been simplified to 8 shades of gray instead of the original 66 and 16 respectively.

Mod:  Gave the same treatment to the "Cursed Earth" mod's grass.

Optifine:  Red sandstone now connects more seamlessly with lower levels.

Optifine:  Switching between the Nether and the End now has more appropriate loading screens.  Might need to make the end's a little darker.

Optifine:  Grass overlay has been slightly tweaked to make it less repetitive.  Wish I'd noticed before 19 blocks of support.

Optifine:  Grass overlay now supports concrete powders.

Optifine:  Biomes O' Plenty support for my grass overlay, including mud, mud bricks, flesh, ash, and white and white sandstone.  Including tops of upper variants of stairs and slabs.

Optifine:  Biomes O' Plenty's white sandstone now connects more seamlessly with lower-levels.

Optifine:  Cursed Earth has a grassy overlay as well, now.

Release 9:

*Optifine:  Fixed grass overlay shadows for stone and cobblestone.  Some were converted to solid white backgrounds instead of transparent.  Apologies!

*Optifine:  Cursed Earth now uses the same overlay as grass, but with its own color overlays.  Uses same shadows as grass overlays.

Mod Support:  Cursed Earth grass has been given my change to default grass as a separate model, as the mod's grass has been updated to use color overlays.  Changed model/blockstate files to reflect this.

Optifine can be downloaded here.  If you want to install it with current Forge, you'll need the latest "Preview Version" of optifine, which you can see by clicking the "Preview versions" link at the top of Optifine's download page.