I looked a ROM manager called ROM Manager but it is listed as incompatible with my Samsung Galaxy Nexus.
Does ROM Manager support the Galaxy Nexus? If not, what are the alternatives?
The Galaxy Nexus is supported from a device/hardware standpoint, but it may not be available in your region for some reason. If that's the case, you can instead get ROM Manager directly from the developer's website. There are also ClockworkMod recovery downloads on that page.
If, for whatever reason, ROM Manager proves to be unusable or unsatisfactory, there are a few alternatives currently available: