This morning's massive coronal mass ejection from the Sun got me scrambling around trying to remember details of how amateurs can monitor solar flare activity during the current solar cycle. Mark Spencer, WA8SME, had some articles on building a small monitoring station that detected SIDs, or "sudden ionospheric disturbances". The basic idea is to create a VLF receiver to pick up signals such as the strong one megawatt transmitter on 24Khz in Cutler, Maine, and then graph the overall signal strength and record it on the computer equivalent of a strip recorder. I know I have the QEX article from 2008 where he described this system, but I can't find it. You might find this article to be of interest, as well as the great efforts of the AAVSO (American Association of Variable Star Observers). Here is another receiver circuit that I ran across.. All good stuff.