Not sure about smelting sandstone, but ExtraUtilities has clear glass, crafted by smelting "sandy glass", which is made by crafting two sand with two glass in a grid, with an output of four sandy glass. Clear glass, like all XU glass types, drops when broken. This mod might be a good way to have that one feature isolated apart from the rest of XU.
I agree that tiny mods can greatly improve gameplay. Obsidian Pressure Plates and InfiniBows are perfect examples of this. Up until carpenter's blocks came about, I don't think I could have built a house without Obsidian Pressure Plates.
One more thing: If you're going to post a mod (besides a library), please put pictures or any other sort of media demonstrating the features added. A screenshot of the crafting recipe would be just fine for this mod.