Dynamic Subdomain Generation

I've been looking around, trying to find information about how I should go about setting up a system for dynamic subdomain generation. Here's the way I currently have to create a new subdomain:

1. Add the Virtual Host to httpd.conf
2. Request that the subdomain be added to my Web host's DNS (I'm using a VDS)
3. Wait for the changes to propagate
4. Hope that what I asked for is what I really wanted
5. GOTO STEP 1 As Needed

I feel that I should be able to create subdomains (img.cparker15.com, xml.cparker15.com, css.cparker15.com, dtd.cparker15.com, etc.) on the fly. Is there a way to accomplish this with Apache and/or an Apache module?

I've heard things about mod_rewrite, but I don't know where to begin, if mod_rewrite is even a viable solution.