Yup, fire up Terminal and type:
wget -r -k domain.com
This will recursively go and get all the files referenced by the main site and convert all the links to point locally at the files.
Keep in mind wget is no longer included in OS X so I'd suggest you go and get fink from fink.sf.net. You'll also need the Developer tools installed since Fink compiles everything from source but its very easy. You simply type :
fink install wget
and it does its magic.
You can also look over at versiontracker.com to see if there's a pre-compiled version you can download.
wget is great, I used it to scoop the entire
www.artbell.com site before it went off-line on December 30th. They're we're going to charge money for the contents on CD-ROM, so I just had my system grab it overnight for free.