There are multiple third party products. I have not used any of them yet so this should not be interpreted as an endorsement - I only know about them because I've been looking as well.
I've heard good things about Scribe. Their "Scribe Online" product supports QB. It is on the expensive side in my opinion but if you have complex requirements it might be the easiest option.
If you're ok with some programming, CozyRoc sells an SSIS tool set which includes connectors (not sure if that's the correct term) for both Dynamics CRM and QuickBooks. The product itself is relatively inexpensive.
Inogic has a product called "Inolink: QuickBooks." It looks like it may be less flexible than the solutions above in that it only synchronizes a few specific things, but those things probably cover the most typical scenarios.
I'm sure there are other products that I don't know about. Good luck!