The circle of fifths is a really old idea that organizes tons of music theory ideas- the free Circle of Fifths Decoded E-Book takes it to the next level by drawing lines connecting the chords/notes that make up each Major and blues key.
Understanding how Major keys & the words used to describe them are the keys to getting the most out of Fretboard Toolboxes. Test your Major scale knowledge by filling out the Building Major Keys Worksheet for the keys you play in the most.
Use the Quick Key Decoder to see the chord Roman numerals in all 14 Major, minor, and blues keys, in a way that lets you quickly see how to transpose songs from one key to another. Part of this tool also shows multiple capo positions for each key!