A reverse proxy that sends requests to "mysubdomain.mysite.com" to a machine with a DNS entry for "mysubdomain" (untested)

dynamicsubdomainreverseproxy.py

from twisted.internet import reactor
from twisted.web.proxy import ReverseProxyResource
from twisted.web.server import Site
from twisted.web.resource import Resource

class DynamicSubdomainReverseProxy(Resource):
    isLeaf = False
    allowedMethods = ("GET", "POST", "PUT", "DELETE", "HEAD", "OPTIONS")

    def getChild(self, path, request):
        subdomain = request.getRequestHostname().split('.')[0]
        return ReverseProxyResource(subdomain, 80, '/' + path)

proxy = DynamicSubdomainReverseProxy()
site = Site(proxy)
reactor.listenTCP(80, site)
reactor.run()