In the sense of "item occupying a relatively minor slot that grants a non-enhancement bonus to thrown weapon attacks", I don't know of one. As a DM, I'd be pretty willing to allow a player to acquire a comparable item for throwing attacks with a throwing weapon (not any attack with a weapon that can be thrown) for a comparable price. Throwing as a primary style already carries some overhead that archery does not, so that'd be something that I'd be okay with, but you'll have to ask your DM.
I would probably allow that as a custom magic item I do not know of one that exists though.