It's obvious that you have heard and super-duper-heard Crazy, Gnarls Barkley's big hit. But surely, unless you're a hack laptop DJ who spends too much time trolling webs for hot new remixes, you may not be familiar with the theme tune Nel Cimitero Di Tucson, which is essentially an instrumental Crazy. It really seems like Gnarls Barkley had sampled it! It's wicked interesting to hear the original version and see how it has been modified till becoming the song we all know. Despite the trumpets were replaced by strings, the baseline practically remains the same.
Here you have the original version. Listen to it and keep reading.
In addition, we can not talk about this tune without mentioning its covers. Here are four versions:
Thanx to We're Covering The Original, another cool version track can be included in the list: