I don't know if I would call it "good" but if you're willing to settle for "official" there is http://www.ti.com/tool/MSP430-FLASHER http://www.ti.com/tool/MSP4

I don't know if I would call it "good" but if you're willing to settle for "official" there is http://www.ti.com/tool/MSP430-FLASHER http://www.ti.com/tool/MSP430-FLASHER which will work with TI's own MSP-FET on all three major OSs. Accepts a .hex so you can use whatever toolchain you want.