I have a client using Ubercart who is looking to integrate with QuickBooks. After a bit of searching, I found that Ubercart itself has some discussion of this topic which seems pretty out of date:
Then I found an existing module which does not appear to be production-ready:
And two commercial solutions:
Does anyone have experience with any of these solutions? The site is built on D6, and uses Ubercart with a variety of extra modules, including Ubercart Userpoints module, which allows customers to earn store credit. It will be important to bring information about the store credit, along with sales & inventory, into QuickBooks.