OpenID / OAuth Reverse Proxy

I have a bunch of existing web applications that use either Windows authentication or username and password authentication.

Instead of asking users to keep track of usernames / passwords and Windows accounts (as these applications will be accessible over the Internet), I would just use OpenID. But I would prefer not to rewrite all applications to use OpenID.

I am wondering if there is a reverse proxy that will allow them to register through OpenID and then map the OpenIDs to Windows / username and the reverse proxy to the target web application?