"Prophets" by A.C. Newman ;)
Season 5, episode 17 - Of Course
Doppelgangers (Season 5, Episode 24)
The last episode of How I Met Your Mother has not aired yet. The producing team have made mention that the next season, 8 may be their last season.
Shine - Lovefreekz
(2x16) Stuff
Hooked - Season 5
How I Met Your Mother especially season 4, he loves "The Naked Man" episode
It was Season 5, episode 12, Girls vs. Suits.
The song was featured in the fifth season of How I Met Your Mother in an episode called "Home Wreckers".
Sandcastles in the Sand (Season 3, Episode 16).
Season 4, Episode 11 if I am not mistaken ;-)
The Bracket (Season 3, Episode 14).