Standard 12-bar blues is the most well-known and popular blues. Listen to just about any blues player for some of this. Status Quo also used this for their rock stuff. Rock often uses these progressions but tends to be more with 16 bars, since this is a more 'natural' dance feel, ie. 4 groups of 4 bars.

There's also Chicago blues (tell me if I'm wrong here - oh hell, I don't need to say that here ;-) which tends to repetition of the same chord sequence over and over (sometimes with minor changes) as the singer thinks up new words, although this usually goes in 12-bar units, and sometimes has slight changes to make it a bit more 12-bar blues-y. Get a John Lee Hooker record for some of this. The original Boom Boom recording falls into this category, although there are other versions of it done in a standard blues progression too! A fairly standard Chicago blues rhythm goes (pause) A G E (pause) A G E.

I'd guess the repetition of the same chords allowed you to make stuff up on the spot. This is traditional in African music where a common tune is used for spontaneous words, so it may well have been carried over since most black music involves a good deal of spontaneity. That's my theory, anyway. Anyone with more info on black tradition who can explain it better?

Grab.