I have a proof-of-concept of the gnirehtet Java relay doing a DNS intercept. This allows to run apps in the phone and then see in real time what type of DNS queries they perform. I will be happy to work together with others in cleaning up and extending the proof-of-concept for release.
DNS intercept as a standalone tool exist, what I like about doing it at the reverse tethering stage is that the phone is completely sandboxed. It also allows to detect access to IPs that come hardwired in the phone.