I found silver, and while it seems to be used in the Factorization mod, the Silver entry in the Factorization wiki is missing. What's it for?
- With Nikolite in an Alloy Furnace to make Blue Alloy Ingots
- With a stick in a crafting table to make Athame, a dagger strong against Endermen
- Used to make Glass Fibre Cables along with glass and a diamond
In Thermal Expansion:
- Used to make a Redstone Transmission Coil used in a Steam Engine
- Used to make a Crescent Hammer along with Iron
- Used to create Wrathlamps along with Dark Iron Ingots
- Used to make Reflective Mirrors which are used to power Solar Turbines
And ofcourse you can pulverize it to get Pulverized Silver which you can combine with Pulverized Gold to make Electrum Blend, which is used to create Electrum Ingots which is used by Thermal Expansion and GregTech.
In Thermal Expansion it's used to make Redstone Energy Cells.
There are a few more uses, just check the wiki or use NEI for it.