Hey guys,

Not sure if this is the right forum so thought id pop it here as this seemed best.
I have a friend starting a business and I said id lend him a hand.
He wants to find a system for invoicing and receipting payments that prefferably runs online (preferrably PHP but not essential) and also since he is just starting preferrably something open source or free.

Anyone have any ideas? I have googled but nothing seems terribly complete?