S.A.M. was a robot designed to help the local weatherman Vance Vetteroy with his broadcasts of the weather. Its name stood for Sounding Autonic Meterograph.
Vance was greatly annoyed that his creation was reduced to a TV gimmick, and so attempted to redesign S.A.M. in hopes of giving it the ability to control the weather rather that merely report it. During the test run, S.A.M. was struck by purple lightning and developed a somewhat HAL-like personality, albeit with more emotion.
For some reason, S.A.M. decided to use its new abilities to wreak havoc (why is never explained, though such events would certainly be newsworthy). Ben was able to take S.A.M. offline with help from Grandpa Max and Gwen by using a guitar to produce a sound frequency at the opposite end of the spectrum from the hum given off by S.A.M., thereby neutralizing the machine.
The Water Monster was an entity that was created by S.A.M. When S.A.M. first created it, it caused a torrential downpour at the concert. It was turned to steam by Heatblast.
Another form of S.A.M. is the Cloud Monster, a thunder cloud. When S.A.M. first created it, it reigned down thunderbolts all over the city. It was shorted out by salt.
Different Elements Monster
S.A.M. also turned into a monster made up of different weather entities and had Vance Vetteroy trapped in it. It was S.A.M.'s final form before being destroyed by Four Arms playing some electric guitars.