Building your own bicycle wheels seems like a worthwhile pursuit. Since most bikes people buy these days are simply pulled out of a box and assembled by the seller, being able to properly set up your own bicycle would be a very useful skill. Although I guess if you can tell the difference between a well setup bicycle and one straight out of a box, you would probably buy it from a good bike store that will set it up for you before you take it home. Still, an interesting skill.