I spent some time last night playing with Shiira, an OS X native browser built using Cocoa. Shiira feels very fast and has a very slick user interface making it very comfortable to use from the get go. Shiira has a laundry list of great features including:

• RSS support
• Page holder
• New application icon
• New sidebar design
• Sound effects and font smoothing switching, to improve universal access support
• Tab Exposé
• Page transition effect (Tiger only)
• Open All Links in Tabs
• Browse mode in the toolbar
• Private browsing
• Firefox bookmarks

My favorite feature is the tab expose which allows you to iconize your tabs and reorganize them in a very user friendly way. While Shiira is still a baby and does contain some known issues, it is much more useable than Firefox 1.5 (at least on the OS X). I love Firefox, but I’ve been frustrated with a very nasty bug with Firefox 1.5 in OS X where pressing the mouse button causes Firefox’s memory usage to go thru the roof.