In this staggering eight-minute video, you take a guided ride on the Solid Rocket Booster alongside the Space Shuttle. The video is interesting but the sound is astonishing -- put on your headphones, watch this, and read the YouTube annotations as they pop up (it may help to make the video fullscreen so they're more legible). Apparently Skywalker Sound helped to mix and enhance the audio, to give you something like the real experience of being strapped to an SRB. My favorite sound is at just under 2:00 in the video, when the shuttle separates from the first section. Just wow.
For more on the SRB, check out Wikipedia's exhaustive SRB page. This video is apparently part of the "upcoming Special Edition Ascent: Commemorating Space Shuttle DVD/BluRay" which, as far as I can tell, is still upcoming. The trailer for the film is enticing, to say the least.
Also very much worth a look: Space Shuttle Endeavour’s Final Launch.