Watch the Tweaking the 7th online guitar lesson by Jeff McErlain from Blues Guitar Survival Guide - Lead
Just like tweaking the 3rd, another note we can manipulate is the b7 of the minor pentatonic scale. This is a great sound and should become as second nature as the tweaked third. One thing to make note is that this 7th is a whole step below the root as opposed to the half step tweak of the third so it requires a little more practice to pull it off with finesse. If you put in the time to perfect the nuance that the two of these bends can add to your playing you will sound better in a very short period of time. You will also wonder how you lived without them!