Do not be put off by the wacky name, Cyber Duck is a seriously good FTP client for the Mac. I have been using Filezilla for a while and find that it is not so reliable as the PC version. Having tried Cyber Duck I think I will drop Filezilla. Cyber Duck is free and more integrated into OS X. It is also closely tied to Text Mate which is a bonus!
If you tire of editing your hosts file in VI or you need a customer to be able to do it themselves to point to a development server, there is a superb little widget which enables a non technical user to edit their hosts file.
I have had problems browsing some sites on my iMac using Leopard OS X 10.5. All i get is a blank page and in the page title "gif image, 1x1 pixels".
After some searching I discovered that it was related to Net Barrier X5. There is a setting in the Surf > Banners Filter which was causeing the issue. Simply unclick the "Filter banners" setting and your sites will be visible again.

Updating a hosts file on a mac in OS X Leopard is a little more difficult than a PC.http://www.apple.com/downloads/macosx/internet_utilities/hostal.htmlIt is possible to edit the hosts file direct but it is a bit techie on OS X. You need to do EXACTLY the followingYou must have access to log in as the root user - http://support.apple.com/kb/HT1528?viewlocale=en_US