There are lots of websites but all sites I know are aimed at researchers (so not intended for the general public) and usually apply to a specific country only.
Take for example this US Life Cycle Inventory Database. It contains inventories for various materials and services (lists of input and output for producing something) which can be used to calculate ...
I wouldn't call it comprehensive but it is what you're looking for.
A cursory web search lead to this and many more sites.