Here's a list of some programs that you can download for free or find via a google search to supplement the software that comes with your mac.
carbon copy cloner
See the entry on backups, this application allows you to make a bootable backup of your hard drive. Superdooper, a newer program, seems to be a more popular backup program and simpler to use, but it's not free so I still use CCC.
skype (voice over IP)
Skype allows you to speak to other skype users anywhere in the world for free over the internet. Simply download skype, create yourself a 'skype name', this is your unique skype name, and you are away. You don't need to pay any money unless you want to make a call to a normal phone number. If you have an imac or a powerbook or ibook you can use the built in microphone and speaker, but for better results use a headset microphone which will stop any 'echo' you may experience. Your friends need to have their computer on when you search for them in skype for the first time, or skype will not find them.
A great little text editor, like textedit, but many features such as search and replace on multiple files without opening them, automatic formatting for html, compare two different text files and show the differences, open and edit text files over ftp, if you're not sure why you'd need those features, stick with textedit!
mac the ripper
Allows you to capture a DVD from your DVD drive, then view it in quicktime. Good if you just want to watch one chapter of a DVD, or if you want to watch a DVD in the car without running your laptop battery flat - it uses much less power to watch a DVD from the hard drive than from the DVD drive.
Fantastic application, hard to explain how to use it and what it does, but I use it probably at least 20 times a day. It allows you to do many things at the press of a key, like a shortcut, but without you having to remember what key does what, because it guesses what you want to do by what you type in, and it learns, very clever. It takes a bit of learning, but the time you save after learning it is well worth it.
As it says, allows you to combine multiple pdf documents into a single pdf documents. For example, combine a single page pdf from pages with a pdf printed from a screenshot with a pdf from illustrator all into one document of three pages.
Cocoa Booklet takes a multi page pdf file (eg 16 pages long), and makes it into a booklet by moving all the pages into a different order so that when you print it double sided and staple it into a booklet, all the pages are in the right order - like Microsoft publisher does on the PC. You can reduce the size too, ie make an a5 booklet from a4 pages.
Allows you to record any sound from your computer (skype conversation, itunes song, streaming audio, movie soundtrack etc) to an mp3 file. THIS IS NO LONGER FREE.
LAME engine for itunes
See separate entry under music, this imports your itunes songs at a better quality than the itunes encoder.
A free piece of bible software, easily the most simple to use, now available for OS-X as a beta release. Does searches on words in english, or greek/hebrew. A good cross reference system. Allows you to paste bible text into any application (eg Pages) with a hotkey.
A full-featured audio recorder. It can record audio with a level indicator, then process the audio (speed it up, slow it down, raise or lower the pitch, compress, normalise etc) and then export to mp3 or other formats. Stick with the simpler 'soundstudio' if you don't need these features.
An alternate browser for OSX that on it's own is about equal with Safari in my opinion, but it has lots of plug-ins that enhance it with features such as ebay auction tracking, viewing and editing CSS source code, monitoring your monthly ISP downloads and heaps more.
Also, you can learn more share software, you can free download it, then try it, if you are satisfied, you can buy it. Learn More: Mac Share Sofrwre.
beat maker for mac free os x
Find out more: Beat Maker For Mac Free Os X