More bass lines - Minor
Yesterday we looked at a bass line that used the Flat-7th as its primary color note, giving it a bluesy feel by omitting the Major 3rd and Major 6th of the previous bass line examples. If we use the Flat-3rd as well we really move towards a dark feel, making it debatable whether we're in minor at that point.
Here's a great example: 2 2 2 3' 4+ (think "Green Onions" by Booker T and the MG's for rhythm here http://www.youtube.com/watch?v=U-7QSMyz5rg, they're in F by the way, B-flat harp)
You could also play a bass line like this in a shuffle rhythm...
2 2 3' 3' 2 2 2" 2"