Job Management Systems: Large Scale Wide format Organisations

Do the big boys use in house inbuilt software to meet their needs or are there packages on the market that let these organisations quote, invoice, produce and deliver work based on flexible pricing rules (area based pricing that gets discounted with larger quantity)?

Features like job proofing and approval, job tracking information, partial shipments, web2print front end etc etc.

Most organisations I know have their own built databases using FileMaker pro and custom interfaces.

I'd like something web based with an API to tie into our accounting and debt control systems as well as merchant facilities.