I think it's often about the angle you come from, rather than necessarily the angle you hit the line at.

Take this try from Ben Cohen: Cohen try

He comes from a wide angle to take the ball tight from Wilkinson at the last minute. The defenders have been drawn out, and he beats them by cutting back on their inside.

Another example of this comes through Scott Gibbs try against England in '99: Gibbs try

Again, he comes late from wide to tight, leaving the defense no time to adjust. This technique works well, but only when timed as late as possible. Too early, and the pass is telegraphed for the defenders.

On the other hand, if you have the raw acceleration of Matt Giteau, you can ghost around defenders like this: Giteau