Songs that sound alike

Ever listen to a song only to swear that you’ve heard that melody before … possibly in another song? Ever wonder if someone’s intentionally ripping someone else off? How much do you have to sound like someone else before you step past that “influenced by” label and gain the less praiseful “derivative” moniker?
Here’s a cool website which does side-by-side comparisons of some famous songs that sound alike. Here are some interesting examples::
“Inbetweener” by Sleeper vs. “Superman” by Five For Fighting
“Different Kind” of Tension by The Buzzcocks vs. “Bruise Violet” by Babes in Toyland
“Tra La La” by The Banana Splits vs. “Buffalo Soldier” by Bob Marley
“Let Me Down Easy” by Chris Isaak vs. “Take Me Home” by The Tuesdays
Alfred Hitchcock’s “Psycho Theme” by Bernard Herrmann vs. “Re-Animator’s Main Title” by Richard Band
Thomas | Similar-Sounding Songs