I am a web developer and have just started a project making some tools/apps for jewelry making:
The site currently has a casting calculator / metal conversion calculator. You enter model weight (in wax or precious metal), select target material and see cost and weight). There are also some charts with live prices of gold karats 10 - 24, sterling/fine silver, platinum and palladium.
If anybody is looking for particular tools like this to make their workflow easier, would love to hear any suggestions, or feedback (good or bad is welcome)!