MurderHobo now has a free demo. Better late than never, right? It's working its way through Desura's approval process now, but you can download it from my website for Windows and Linux. (Mac users, I haven't forgotten about you. Mac demo coming soon.) UPDATE: Demo is now available on Desura too. Thanks guys!
Saves from the demo carry over into the full version. You can start playing in the demo, buy it if you like it, and then pick up where you left off.