How can I set up a local host with a reasonable name, different than "localhost:80"?

I realize that the OP has a mac, and that the solutions given work for both mac and linux.

But I would also like to add that Windows has a hosts file too in C:\Windows\System32\drivers\etc\hosts, in case someone comes here through google with the same problem and uses windows :)

The Webserver can't do that for you, as it's not responsible for DNS resolution.

You'll need to add an entry to your Hosts file (/private/etc/hosts or /etc/hosts depending on the version), and then perform some special MacOS X magic ritual to make it stick.

You can do this by editing /etc/hosts (you will need to do this as administrator, e.g. sudo nano /etc/hosts

Find the line that looks like:

127.0.0.1    localhost

And add another hostname, e.g.

127.0.0.1    localhost mydomainoffline.com

(Edit: I should point out that while this works just fine for Leopard (10.5), I don't know about other versions of Mac OS X)