Here are a few applications (with links) for Apple's Mac OS X that you might find useful. See the download site details for the requirements for each of the applications.
AdiumX - This great application handles multiple types of chat (including, but not limited to, AOL Instant Messenger [AIM]) and Yahoo Messenger. I believe it's based on gaim, and what I really like about it is that it's really out of the way when you want it (iChat was always in my face) and it's really easy to tell who is messaging you (by display in the Dock). FREE.
Obviously, Safari is a great web browser. But Firefox is pretty good, too, especially if you want all the customizable themes and extensions. FREE.
I like NeoOffice (based on OpenOffice.org) because it integrates well with OS X and can open Microsoft documents. An issue I have with the current veresion of NeoOffice is that it tries to save in its own format (I usually just default to Microsoft formats for compatibility with my PCs). NeoOffice (at the time of writing) is slightly out of date to the OpenOffice.org 2 Office Suite, which is a great (although large) download. Both are FREE.
(Note: OO.org requires X11, either downloaded from Apple.com or found on your Mac OS X CDs/DVD).
I found a little gem called Fugu which is great for secure FTP sessions you'll need to hold at the coffee shop. Cyberduck is great for FTP also. Transmit is pretty cool although after the trial period it'll cost you a few bucks. Fugu and Cyberduck are FREE/donationware, Transmit is $29.95.
Here's where it gets a little pricey. The two main FREE options are Gimp and GIMPshop (based on the same project) which are pretty cool, but if you're used to Photoshop, you might consider the $100 Photoshop Elements (On Sale for $75 at MacMall.). Even better, buy a Wacom drawing tablet for less than $100, and you get Photoshop Elements FREE in the package!
(Note: GIMP/GIMPshop requires X11, either downloaded from Apple.com or found on your Mac OS X CDs/DVD).
For a graphical text editor for coding TextWranger is a great piece of software. I have no complaints about it and love the sidebar for when I'm editing multiple files. FREE.
I like Second Life because you can create stuff in it and its
into an adult server and a teenager server (so if you're 30 you won't get
stuck with 14 year-olds, and if you're 14 you won't get stuck with 30
year-olds). Second Life is FREE through this link.
Also worth a look is PalaceChat (free trial) and The Manor (free trial). These are mostly 2D chat environments, with people of all ages.
For those who like strategy games, FreeCiv is a great option.
For casual (read: regular user) backup, the Backup software supplied by Apple is pretty darn good. Online backup via the .Mac service ($99~ a year) is fast and reliable [if you're on broadband, at least]. I don't have any recommendations for other backup software at this time, but I'll add them as I find them.