Prem Sikka has been arguing in favour of unitary taxation in the Guardian. He's right to do so, but it is only fair to say we are working on research on this issue together righ now. As he says:
The unitary taxation model should be debated at the next G8 meeting. It can easily be applied to EU member states and beyond. There is plenty of room for negotiations around the apportionment formula and related factors, but the ultimate prize of making a serious dent on organised corporate tax avoidance is worth pursuing.
It's more than that: the OECD has promised radical reform and unitary taxation is ultimately the only alternative to the current failed systems.