There are a number of OSX backup utilities, but nothing exactly like Ghost. The closest thing for individual users is Carbon Copy Cloner from bombich.com. (shareware) If you have a server, there are ways to automate the restore process using his NetRestore, but that's mostly of interest when you have multiple machines to support. CCC can duplicate a disk to another disk (separate files) or to a single disk image file.
While you can make blank disk images with Apple's Disk Utility or the command-line tool hdiutil, keep in mind that the Finder cannot see all the files you will need to copy to an image, so you'll need something more comprehensive. CCC is really just a GUI wrapped around a couple of UNIX commands that move the right files.
Also, most backup progs. will require you to be booted from a different disk than the one you are imaging, such as a CD or external firewire drive.