If you are using DSL or Cable,
1. Buy a wireless router, connect it to your DSL/Cable modem.
2. Go to DynDNS.com, sign up an account and a free domain, something like yourdomainname.mine.nu or so.
3. Configure your router to enable dynamic DNS service and port forwarding (e.g forwarding 8080 to your local server's 8080)
Hope it helps