Help! What is this song?

Originally Posted By KristinPlease help me! I have heard this son, it sounds like a lullabye, but maybe it is not actually classified as a lullabye? If anyone is an ER fan, it was on Dr. Green's last episode (when he past away). They played it as he was thinking back on his life. It starts out with "Somewhere over the rainbow...", but then turns into a medley of other songs. If anybody knows what I am talking about, please let me know! Thank You!