Would be great to have an ebuild for the Venom Tox client: https://github.com/naxuroqa/Venom The published releases are extremely old and outdated, though. Upstream creates binaries from snapshots of unmarked revisions: https://wiki.tox.im/Binaries
P.S: Venom works reasonably well now and is quite stable. It is able to run video calls where SIP based tools or Skype fail due to firewalls, even though the image quality is worse than with µTox. It's UI is far better than that of µTox (it has better looks and features like mimise-to-systray or local contact name aliases). Video calling is incompatible with µTox at the moment.
I hate to say this, but development on Venom has ceased. We recommend that users instead use qTox or uTox as a Tox client; both of which are available in our official Gentoo Overlay at https://github.com/Tox/gentoo-overlay-tox.