Automatic subdomains with Apache
Solution 1:
I've answered my own question.
Here's what I put in my Apache config:
<VirtualHost *:80>
VirtualDocumentRoot /var/www/hosts/%0
ServerName jason.mydomain.local
ServerAlias *.jason.mydomain.local
</VirtualHost>
Then, in /var/www/hosts, I put a directory called jason.mydomain.local. That's all it took.