Thought it might be useful to you Mac virgins if I gave you a list of some of the apps I use regularly...
Evernote - it works on Mac, iphone, ipad, android, etc - great for synching notes between devices https://www.evernote.com/
Dropbox - Share files across devices... again, great for synching information. 2GB storage free... http://db.tt/9DiL5uf
TextWrangler - handy text editor http://www.barebones.com/products/textwrangler/
Audacity - Audio recording and editing http://audacity.sourceforge.net/
VLC - Multimedia player that plays just about anything http://www.videolan.org/vlc/
Miro - another media player - http://www.getmiro.com/
Perian - improves quicktime to support multiple other formats - http://perian.org/
CoconutBattery - utility for keeping an eye on the health of your battery http://www.coconut-flavour.com/coconutbattery/
Doubletwist - if you have an android device, this is good for syncing stuff to your android platform (music, phtos, etc) http://www.doubletwist.com/
Filezilla - ftp/sftp client http://filezilla-project.org/
Google quick search - never look for an app in the applications folder again! http://www.google.com/quicksearchbox/ - this is probably one of my favourite apps.
Handbrake - DVD ripper and video transcoder - http://handbrake.fr/
Mactheripper - Another DVD ripper - http://mactheripper.en.softonic.com/mac
Gimp (needs X11) - quirk but powerful graphics editor - http://gimp.lisanet.de/
Inkscape - vector graphics editor - http://inkscape.org/
Keepass - Password security / storage - http://www.keepassx.org/
Truecrypt - If you need to encrypt disks - http://www.truecrypt.org/
Neooffice - like openoffice, but a mac osx build - http://www.neooffice.org/
Stuffitexpander - for handling zip, rar, tar, gzip, bzip archives etc - http://www.stuffit.com/mac-expander.html
SuperDuper - disk imaging - http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
Carbon Copy Cloner - another disk imager - http://www.bombich.com/
Adium - instant messaging client - http://adium.im/
Transmission - bittorrent client - http://www.transmissionbt.com/
ClamXav - antivirus - http://www.clamxav.com/
Xquartz - for those old apps that still need X11. X11 is built into OS X, but not always the most up to date version - http://xquartz.macosforge.org/trac/wiki
That's it really.... more MAC hints and tips to follow!