To ME, he looks like...
a younger Stan Kirsch (I don't think he looks like Matthew McConoughey (sp?) or Owen Wilson, as some others do - maybe just the hair, when Ryan wears it long-ish :)
Stan's not super famous, but anyone who is/was a huge 'Friends' fan might remember him best from the episode, "The One with the Ick Factor," whereby he plays 'Ethan', a younger guy who Monica dates. He leads her to believe that he's a senior in college, which makes him a bit 'young-ish' for her; however, when she finds out that he's actually 17 and a senior in high school,she mortified and worried that it makes her a (maybe) felon, lol.
Here's a pic of him, when he was in his late 20s:
http://www.aveleyman.com/ActorCredit.aspx?ActorID=9472