It looks like there are some decent inventory tools available such as nventory. I'm having trouble finding anything that even makes a stab at tracking costs, though. It doesn't have to be perfect, but I'm looking for something that can track instances, storage, and bandwidth used by EC2 instances. Handling S3 would be nice too, but .. EC2 is a start.
Does such a thing exist? I'm having trouble even googling it, since Amazon's (retail) inventory management system fills my results.
To restate, my question is: what's the best option for tracking Amazon AWS usage?