My fav. app is an Ftp client named Gideon. it has secure ftp. its brand new just released about a week or so ago. its free to try and if you like make a purchase. prices not bad either. check it out at http://www.GideonSoftworks.com
Granted it's not Mac only but my app of choice would have to be Adobe Illustrator. And you can't beat a bit of iTunes to provide inspiration while you work.
Another cool app is CandyBar it takes all the hassle out of customising your Mac!
1. Salling Clicker - god its soo cool to here iTunes auto-pause when I walk out
of the room...or hear my mac say "Welcome Back" when it
detects me walking back in...
PhotoShop Elements 3 - I have a mountain of old family pics that need repair and this does the trick.
iStock - I'm old enough to worry about retirement so I monitor my IRA. Love the price of APPL since I bought way too few shares at $14.85!
iPasteboard - saved my life converting from a WIN accounting program.
QuickBooks - run my own very small business and am bookkeeper. Decided to drop the last XP app - accounting - and go all Mac. This was the best for me.
Currencies Converter - I have clients overseas and this is very handy.
Book/DVD/CDpedia - Always seemed to buy books on the road that I already own. Decided to establish an inventory to avoid this. It's also nice for insurance purposes as it lists the full price of every book. Delicious Monster now has Delicious Library which holds everything, allows you to use iSight to read the barcodes and will download a copy of the card file to your iPod.
Burning Monkey Mahjong - helps get me through 14 hour long haul flights.
@-Time - time in multiple time zones, helpful when you need it.
iLife & Safari - because Apple does it so much better than MS.