According to https://eosflare.io/account/eosio.ramfee:
eosio.ramfee By eosio (6/9/2018) Total Balance 1940285.4732EOS ≈ $4881448.27USD ($2.5158/EOS)
Who can spend this [system] tokens?
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These are locked and are waiting on a community decision on how to use them. Ram fees plus name auction fees will probably be added to the Resource Exchange (REX) pool. This will be paid to accounts that lend their EOS to the REX. REX will enable developers to lease resources for a fraction of the cost of buying EOS with a time limit of 30 days with an option to renew continuously.
REX was developed by Block.one and is being tested by the community.
Another option is to burn the RAM fee collected which will effectively reduce the inflation of EOS. This could be decided by the community.
A referendum mechanism is being developed by the community to help vote on these issues. Interesting times ahead and important changes are coming.