Proposal: Theoretical Physics (but not restricted to it)
Remember, if you want support a proposal during commitment phase, aside from advertising it to gain more followers, you can also help increasing the progress of commitment phase by actively participating on other SE sites (and thus gaining reputation).
Especially for Theoretical Physics I recommend asking questions on physics.SE - there is no upper limit how challenging1 your question can be there so feel free to ask research questions. Should the both sites make it out of beta, your question can still be migrated.
1 I mean in the scientific meaning