Rxpert83
Dr. Feelgood
This is a nice little feature that many of us have used in some form or another in the past. Go give tassadar a big thanks!
MultiROM allows you to boot different ROMS or kernels from your internal memory, or even a USB flash stick!
The dev explains it better than i do
He even uploaded a youtube video
https://www.youtube.com/watch?v=JDnDNxqfSaw
For more information & warnings, check out the first few posts of the thread here:
[MOD][DEC 15] MultiROM v19 - xda-developers
MultiROM allows you to boot different ROMS or kernels from your internal memory, or even a USB flash stick!
The dev explains it better than i do

tasssadar[/quote said:MultiROM is one-of-a-kind multi-boot mod for Nexus 5. It can boot any Android ROM as well as other systems like Ubuntu Touch, once they are ported to that device. Besides booting from device's internal memory, MultiROM can boot from USB drive connected to the device via OTG cable. The main part of MultiROM is a boot manager, which appears every time your device starts and lets you choose ROM to boot. You can see how it looks on the left image below and in gallery. ROMs are installed and managed via modified TWRP recovery. You can use standard ZIP files to install secondary Android ROMs and MultiROM even has its own installer system, which can be used to ship other Linux-based systems.
Features:
* Multiboot any number of Android ROMs
* Restore nandroid backup as secondary ROM
* Boot from USB drive attached via OTG cable
He even uploaded a youtube video
https://www.youtube.com/watch?v=JDnDNxqfSaw
For more information & warnings, check out the first few posts of the thread here:
[MOD][DEC 15] MultiROM v19 - xda-developers