The Big Bang Theory - The Lunar Excitation Season 3 Episode 23 While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

Season 3, Episode 22 There are no featured links available

Season 7, Episode 21 What's In The Ground Belongs To You

The Big Bang Theory - The Spaghetti Catalyst Season 3 Episode 20 When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy

The Big Bang Theory - 3x19 - The Wheaton Recurrence

Season 3, Episode 17 - "The Precious Fragmentation" When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.

The Big Bang Theory - The Excelsior Acquisition Season 3 Episode 16

Season 3, Episode 15 - "The Large Hadron Collision" Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.

Season 3, Episode 14 - "The Einstein Approximation"

The Big Bang Theory - The Bozeman Reaction