Asteroid Capture
It is events like this that lead to capture of an asteroid into an Earth-crossing orbit (i.e. a regularly Earth-crossing orbit, rather than a random orbit that intersects the Earth).
Fortunately, there appears to be a timeframe of millions of years before the final intercept, otherwise, the Earth would have more dents in it than it does...
(All of the events discussed appear to be ~100m or smaller-scale bodies. For a rational discuassion of the effects of a close pass by a multi-km scale body, read the intro to "Rendezvous with Rama" by A.C. Clarke, as advertised elsewhere...)