Native GTD "Waiting For" report

Hi. I'm doing GTD with TaskWarrior and I tag items with a `waitfor` tag in order to "wait for" someone else to do this task. It's quite handy and a central part of doing GTD.

Can someone add a more elegant way of dong this? Having a magical tag requires all reports fo filter waitfor-Tasks out. Having waitfor-Tasks is very handy since one can have dependencies on them.
e. g. "I can't do the report because bob hasn't sent me the figures yet".

This is something which GTD users would enjoy and Non-GTD users could ignore easily.
Thanks!