1. Create a nice little chord progression on a guitar, or a keyboard, and record it.
2. Take a guitar, and tune all strings one whole step down.
3. Jam along with the progression: you will need to mentally transpose chord forms and scales.
4. Get another guitar, if you are lucky enough to have one,(I use my acoustic.) Close your eyes, and tune the strings to an open chord, use your imagination.
5. Jam along with the previous progression. It will make you try new fingerings and chord shapes.
6. I know...DOH....you guys already do that.
7. Try it again.
jqs