One mark of a skilled crafter is the ability to use hand tools like a plane.  A good hand plane is a valuable tool that can help you flatten boards the mechanical planer cannot.

Rockler Page

Chisels are very valuable--both in cost (for a good set) and in their worth in the shop.  They are essential, and knowing how to use the can make the difference between mediocre and fine finishes to your joints and projects.

A Lengthy but Comprehensive Guide

Another Good, Comprehensive Tutorial (start at 9:30)