Which organic compounds have the most strongly negative enthalpies of formation?

I've been using the [NIST Webbook](http://webbook.nist.gov/chemistry/) to list organic compounds and look at their heats of formation (kJ/g, not mol). If I limit myself to three carbons, I still get over 400 results.


I can use some heuristics to guess which ones have strong heats of formation. I'm interested in kJ/g rather than /mol so smaller molecules are more likely, and certain bonds like $\ce{C=O}$ help, but that's not good enough for my project because I need to be certain.


Oxamic acid, ammonium formate, and ammonium acetate are up there, but who knows how many I might be missing, limited as I am to looking up small molecules?


So I'm hoping someone with a lot of experience might tell me something off the top of their head.


