A communique intended to spread awareness of an issue, typically through mass media such as amateur radio or the Internet. Sometimes knocked by detractors for unapparent reasons - voting doesn't raise money for anything, but voting is still important. Self-Injury Awareness Day doesn't raise money for anything, but awareness is still important. The entire point of a signal boost is that if you can do something more significant to help, you do that as well as participating in the boost, but if you can't, you boost to help reach those who can.
Tamara says she's standing on an eighth-floor windowsill and I don't know where she lives. Signal boost 'til we find someone who does.