Getting a constant hostname without paying for static IP's from your ISP

AFAIK, this is 100% legal, and doesn't really exploit any sort of loophole.

Just sign up with dyndns.org, or other similar organization. They will provide a mapping from a consistent name, to whatever IP you've DHCP'd to most recently.

Recent DSL/Cable routers include built-in support for sending your new IP address to such services. (EG Linksys WRT54G)

Older DSL/Cable routers may require a cron job that performs basically the same function, by periodically polling your DSL/Cable router, and sending the address to the dynamic DNS service. (EG Linksys BEFSR11)

I really like always being able to ssh to my home box with just "ssh -X stromberg.dnsalias.org", instead of having to somehow log what my new address is and/or portscan my ISP's address range.