Similar Films?

In the sense of the film being about a guy who is normally guarded opening himself to new experiences then biting off more than he can chew I'd say:
-Simon Killer
-Kiss Kiss Bang Bang
-The Bourne Identity (minus the espionage and ability to fight)
-Yes Man
-becausetheinter.net (Donald Glover's screenplay for the album)

"The Internet is a communication tool used the world over where people can come together to bitch about movies and share pornography with one another."

Lost in Translation
Hostel (sort of)
Maybe some Wes Anderson films

Immediately when Charlie Countryman was over, I thought to myself, "I've seen this movie before, and it was called 'True Romance'."

Not that I didn't like Charlie Countryman for it's own merits, but it feels quite a bit like TR.

http://www.imdb.com/title/tt0108399/reference

The Beach
Go
Both similar but not quite, if that makes sense...which it doesn't.

this movie doesn't hold a candle and is barely comparable to true romance.

check out the dreamers, drive, youth without youth.

Spring http://www.imdb.com/title/tt3395184