[justinhj]

There's Charles proxy, seems as good as Fiddler although I'm not a power user. http://www.charlesproxy.com/ For dev tools I use PHP Storm, IntelliJ IDEA and Emacs for everything else http://emacsformacosx.com/

[mountaineer]

Charles isn't free though. Though Telerik will probably screw up Fiddler somehow. For web app HTTP or REST stuff, most browsers do this today too (natively or with plugins, so I need Fiddler/Charles less and less.

[digitalmaster]

my thoughts exactly.. most of the traffic i care about i can already monitor with chrome's network tab.