Joe,
I see that Eddie has already posted about the Circle of Fifth's. That was the first thing I thought of when I read your post. It's probably the most important tool in the realm of music theory.

In 2010 I created BIAB mgu's under the title of Circle of Fifth's Practice files and it covers all of the keys. Each key has 7 different BIAB mgu practice "songs" so there are 84 files in all. They're based around diatonic progressions.

The files cover each of these topics in each key.
1 Diatonic Progression
2 Diatonic Progression w/solo
3 Diatonic Progression - Root Melody
4 Diatonic Progression - Root - Third Melody
5 Diatonic Progression - Root - Fifth Melody
6 Diatonic Progression - Root - Third - Fifth Melody
7 Diatonic Progression - Scales and Modes

I used to have these posted in a shared file on DropBox but I let my account expire and I haven't bothered setting up an account elsewhere. I did post a link to them on the forum in 2010 so I'm not sure if anyone downloaded them or not. If you did you may already have them under the folder named Circle of Fifth practice Files. The folder size is only 545KB.

I may get around to posting them publicly again or I may not. If you want them just send me a PM with an email address to send them to and I'll get them to you.

Bob
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http://soundcloud.com/bobcflatpicke/music-in-the-mountains