Back in the days of Tiger (OSX 10.4) I use to manage hosts with the NetInfo Manager tool but alas this has seen an untimely demise in the Leopard (OSX 10.5) release. You can muck around with your local hosts file if you like but there are a couple of nifty tricks I've found useful.
Apple suggests you use a new utility...
NetInfo Manager is not included with Mac OS X 10.5 Leopard. You can use the command line utility dscl to perform some advanced functions formerly covered by NetInfo Manager. Open Terminal and type "dscl" to access it.
dscl (or Directory Service command line utility) looks a bit like this from the terminal:
sudo dscl localhost -create /Local/Default/Hosts/blog.daemonite.com IPAddress 192.168.200.212 dscl localhost -readall /Local/Default/Hosts
Type man dscl from the terminal for the sort of information that makes you want to stick needles in your eye.