Multiple .local hostname on one computer

I think you don't need to register a new hostname if you're just about publishing web services. On the Mac, you can register a new website with bonjour on the command line with

dns-sd -R "My Website" _http._tcp . 80 path=/path-to-page.html

you can verify that it worked by using Safari's bonjour menu or on the command line with

dns-sd -B _http._tcp

Bonjour for Windows is available (and is, I think, included when installing iTunes).

If for some reason you actually need specific host names, you could consider using dnsmasq (can be installed with homebrew or macports) to reroute your specific hostnames only (using your default DNS for everything else) and telling your Windows computer to use your Mac as its DNS server.

Update:

I failed to realise it's totally possible, you can indeed register multiple .local hostnames with bonjour, do it as a proxy like this:

dns-sd -P myService1 _http._tcp local 80 server1.local 127.0.0.1 path=/path/to/service1
dns-sd -P myService2 _http._tcp local 80 server2.local 127.0.0.1 path=/path/to/service2

Here you're registering two services (myService1,-2) running on the same server (127.0.0.1, within different server paths) on port 80 as two different .local names.