Sometimes when I’m writing or jamming, I get stuck in the same old I, IV, V progression. Not that it’s a bad thing but sometimes I want to mix it up a bit. I found a nice little reference guide at The Guitar Suite that gives you the chords for each degree in scale of the key. The nice thing is that the chart addresses major, natural, harmonic and melodic minor scales which are useful when you want to mess with the feel or color of a song. I recommend using the progressions to warm-up with by playing the scales using the chords.
I will turn to the charts from time to time, especially when I’m spinning my wheels and I find it useful. I hope it helps you as well.