You can use the command line daemon wallet, but currently you'll need to build it, which is quite straightforward on Linux. No standalone miner yet. We're discussing a bounty for a GPU miner to see if an effective one can be made, but it's currently unknown if GPUs can beat CPUs by any meaningful margin, if at all. I'm pretty skeptical. We do want to support pools after the time locked coinbase period is over, but we are not sure yet if that will be through the wallet directly (GUI and CLI) or with a separate miner.