Here is a song with a relatively simple chord progression: Black Magic Woman (made famous by Santana):
Dmin - Amin - Dmin - Gmin - Dmin - *Amin* - Dmin
* OFTEN PLAYED AS Amaj
All of the chords (including the Amaj possibility) fit into the key of D minor (which contains the chords Dmin, Edim, Emin, Fmaj, Gmin, Gmaj, Amin, Amaj, Bbmaj, Bdim, Cmaj, and C#dim). If we analyze Black Magic Woman numerically, we come up with i - v - i - iv - i - v(or V) - i. There are just a few simple chords here, but the tune is very effective - a song doesn't have to contain ten different chords to be great.
