I looked up some free apron patterns online for everyone's edification. Some are plain, some are less so, and a couple are vintage!
Quilt Block Apron (girls): http://www.allfreecrafts.com/sewing/quilt-block-apron.shtml
Plain Historical Apron : http://www.1771.org/cd_apron.htm
One Yard Apron: http://sewing.about.com/od/aprons/ss/oneyardapron.htm
Apron Bonnet Pattern (vintage) : http://tipnut.com/vintage-apron-bonnet-pattern/
Make your own vintage style apron pattern: http://www.girlistic.com/diy/apron.htm
Ten Vintage Apron Patterns (must be printed in miniature and transferred by hand onto grid paper. It would be a pain, but they are pretty cool.): http://www.dorothyshomegoods.com/articles.php?tPath=12
Oh, and a bonus oven mitt pattern: http://www.allfreecrafts.com/sewing/oven-mitts.shtml
Also I found this excerpt from a vintage sewing lesson book on aprons:
" Did you ever stop to consider how many different kinds of aprons there were? A great, big, roomy, coverall apron for mother when guests are expected and important things are happening in the kitchen. A wee bit of a lace apron for the person who is in charge of the tea-urn at five o'clock. A smart bungalow apron to make household duties seem pleasant, and a rather petty apron with deep pockets for the sewing room. And, of course, sweet little aprons for the kiddies—gaily colored and bound with an almost grown-up regard for smartness."