bitcoin-qt creates files under ~/.bitcoin/ in my file system. i know that the ~/.bitcoin/blocks/blk*dat files contain the blockchain, but what do the following other files contain:

~/.bitcoin/blocks/rev*dat
~/.bitcoin/chainstate/*sst
~/.bitcoin/blocks/index/*sst

i know sst stands for "sorted string table" and i gather these files belong to a leveldb database, but i'd like to know in more detail what is in each of them.