Here is a practice track for guitar players in the key of G minor. Its a G minor groove built around a Gm7 chord. Perfect for jamming away on a G minor pentatonic scale. For a different flavour, try a G dorian (Dorian mode of F major) or a G natural minor.
Here is the same track minus the bass line, and with a lead guitar part, especially for Bass players to jam away on. Try coming up with your own bass lines. Also see if you can hear my bass line from the track above, and reproduce it. The chromatically desending organ line that comes around periodically sounds extra good if you double that on the bass.