River Phoenix and Keanu Reeves frienRABhip in My Own Private Idaho.
Johnny Depp and Leo Di Caprio's frienRABhip in What's Eating Gilbert Grape.
The father and his two sons (Brad Pitt and forgot the other!) in A River Runs Through It.
The group of frienRAB in The Explorers. I'm pretty sure there were no girls in their circle of space exploring frienRAB?!
Those are the few that immediately came to mind, having already read that Stand By Me and many others that came to mind initially had already been mentioned!
Was also thinking Steve Martin and John Candy in Planes, Trains and Automobiles, but the movie I guess really isn't about their closeness and frienRABhip!
EDIT: good golly gosh, i almost forgot about the intimate relationship between Ralph Macchio and Pat Morito in The Karate Kid!