i am a big time fan of mac osx. if you think there are no free+useful app for mac, you are quite wrong. here is my personal favorite list of some free and very useful apps which i use everyday.
CyberDuck: it is my most favorite FTP and SFTP client, and its really very cool. Well, you can use it as a WebDAV and S3 client too. Its open source and you can check it out from here
ALunch: if you use your dock very frequently and are really tired to reconfigure it again and again, alunch is a very nice sticky app launcher for you. it’s organiser is simply awesome and you can arrange all your applications in a a well categorized manner easily. its very nice and one of my very favorites. Check it out from here
iStat Pro and Menus: though it has a name “pro” but it comes for free. it is an awesome device monitoring tool and supplies you very essential information about your mac device, like bandwidth consumption (both eth and bt) temperature, fan RPM, memory usage, cpu usage and it supplies each of these with details. download it from here – btw, forgot to tell you that you can install it in your iphone and ipod touch too!
Chicken of VNC: it is a nice VNC client for mac. if you have multiple macs in your home or you want to use it as a generic VNC client to your other machines, from you mac – it is the perfect tool. open source and free :) – check it out from here
Caffeine: it is another very useful and handy when you really dont want your screen to black out (heh heh). it sits on your top bar with a icon of coffee cup, and once you click on it the machine will stay active for 30 minutes (configurable). no screensaver, no dimming – its show time :D. check it out from here