There is no one, single album, but a collection called the American Recordings that were released over a period of a few years, each featuring a mixture of traditional songs, re-workings of Cash's own songs and covers.
These only came about following the surprising success of the first "American Recordings" album that featured (amongst others), covers by Leonard Cohen and Tom Waits.
After the follow-up, Unchained, subsequent albums were then subtitled American III, American IV up to the posthumous American V which was released in the latter half of last year (2006).
It's difficult to recommend any one of these, but for your info;
"Hurt", (Cash's popular NIN cover) is on American IV; The Man Comes Around, along with Depeche Mode's "Personal Jesus"
"The Mercy Seat", a Nick Cave cover, aswell as U2's "one" is on American III; Solitary Man.(entitled after a Neil Diamond track)
Don't forget though that all these albums include some simple, raw re-workings of Cash's own earlier work.
Jump in, buy one (probably III or IV) - and enjoy!