John Ritter, from "Three's Company" and "8 Simple Rules...", due to a heart attack at age 54 (would have been 55 next week, the same week he would have celebrated his wedding anniversary)
Johnny Cash, the Man In Black and arguably the most influential musical figure to come out of Sun Records since Elvis, of complications from diabetes at age 71.
The two, you probably didn't:
Terome "T-Bone" Hannon, a bassist for Jewel's band, of a stroke at age 39. Jewel will be cancelling the rest of her tour (at least his death was good for something).
Kent Poole, an Indiana native who played high school basketball player Merle Webb in the movie "Hoosiers" ("Let's win this one for all the small schools who never had a chance to get here."), of suicide by hanging at age 39.
Anyone feel like playing the Dead Pool? Who do you think will be the next famous person to die? My guess: James Doohan (Scotty from Star Trek).