The Elecraft T1 is a miniature, stand-alone antenna tuner unit that can be used with any low-power HF+6m transceiver. The T1 is available both as a kit or a ready built unit.
The OHR WM-2 QRP wattmeter from Oak Hills Research is simple and easy to build. It measures forward and reflected power from 5 mW to 10 W and is indispensable in a QRP shack.