Accountancy for a webshop/ecommerce system

Hi. I've built a photo-cms (http://mediabeez.ws) to which i now want to add e-commerce support. Adding product-definitions to photo's wasn't much of a problem, and adding a shoppingcart wasn't either. What i'm worried about is the accounting part of a webshop system. I've downloaded some accounting manuals and programs, to see 'how its done'. I've also downloaded some other webshop php apps (notably oscommerce.com) to see how they do things. OS-commerce provides very little reporting. There's no balance sheet, no statement of loss/profits, etc. I'm wondering how a webshop operator/owner would keep track of inventory and profits/losses. Taken to the extreme, a webshop system would require accountancy reporting functionality, a general ledger, journals, etc. How much information would you provide to a webshop owner?