Watch the The I-IV-V & I-IV-V-IV online guitar lesson by Ravi from Guitar Lab: 30 Rock & Pop Progressions
Simply put, the I-IV-V is the most popular chord progression in western music. Most blues and rock songs can be attributed to these three chords, and in fact, a "blues" is pretty much synonymous with I-IV-V. These three are also the only major chords in their key. Coincidence? I think not! When playing these as barre chords, try playing the I with a 5th string root and the V with a 6th string root so that you can stay in the same fret. With your strumming, experiment with "stop time" where you actually stop the ringing of the chord with the palm of your strumming hand in between strums (such as in Summertime Blues).
Examples: Twist and Shout, La Bamba, Good Lovin', Wild Thing, Lucy in the Sky with Diamonds, Tracks of my Tears, Summertime Blues