Levers the IAB can (actually) pull...

The IAB provides input to the IESG regarding BOFs and possible (subsequent) WG formation
Noting that the final decision on WG creation rests with the IESG

The IAB sponsors/organizes the Internet Research Task Force
as well as reviewing proposed IRTF groups

The IAB can convene invitational workshops to perform in-depth reviews of particular architectural issues
See, for example, ftp://ftp.rfc-editor.org/in-notes/rfc3535.txt

The IAB can organize ad hoc bodies of independent experts to adjudicate technical disputes
See http://www.iab.org/about/adhocs/index.html

The IAB can also write informational documents
See, for example ftp://ftp.rfc-editor.org/in-notes/rfc3724.txt
Noting that Standards Track document approval rests with the IESG