We should be running a testnet node+wallet on a daily build that performs some kind of stupid ping-pong transactions, both open to the general public as well as self ping-ponging once an hour or so.
This would give a system level test of the RPC interface, listtransactions, sendmany, keeping up with the chain, signing, etc.
It would also give people trying things on testnet something they can transact with, and create some traffic so that fewer blocks are empty.