Dual boot is not new in Samsung Galaxy devices. Same apply to multi boot on Google Nexus devices. However, I did not try it until now. We can do so thanks to MultiROM. Boot lot of Android ROM no matter stock, AOSP, Ubuntu Touch, Plasma Active, Bohdi Linux or WebOS port. You can also boot from USB drive via OTG cable. Isn’t that great? The easiest way to install – via MultiROM Manager application. Or manual installation which requires you to install MultiROM, modified TWRP recovery and patched kernel. And I believe that Nexus 5 version should come soon too.
Interested? Try it at XDA Forum.