Watch the Minor of the Harmonic Kind online guitar lesson by Chris Buono from Guitar Lab: Blues Progressions
This next progression utilizes the harmonic minor scale to color the changes into something more sinister. Though that doesn't really come across until bars 9 and 10 where an altered harmonic minor ii-V comes into the mix. About that, anytime you see a ii-V with the altered tones you have here you can safely label it as a harmonic minor ii-V. That is, a iim7b5 and a V7b9b13. Be aware the latter chord could be written as a V7#5b9 as an enharmonic equivalent.
Another plus to the treated chords is they have a more pronounced sense of movement. For instance, the climax heard in bars 9 and 10 is far more, well, climatic than say, what you heard in the previous progression. If you want to drop a back cycling two-beat ii-V in bar 8 to setup a iim7, this would be a great sound to go with.
So far these first two minor blues progressions have been on the funky side. Why? Because minor blues seem to fit so well in that vibe. This is not to say you can't swing a minor blues, and, of course, there's the all-powerful minor blues ballad. That all said, expect minor blues progressions for the most part to be on the fonky side. Yeah, you read right: FONKY!