Set of applications I daily use in Mac:

Safari (General Browsing)
Firefox (Web development + StumbleUpon)
Mail (Emails)
iCal (Calendar Entries)
Skype (Client Chat)
MAMP (Web development tool)
TextMate (GUI for development)
Terminal (SSH and SVN)
Filezilla (FTP uploads)
Spotify (Music)
Stickies (Todo list)
Blogo (WordPress blogging tool)
TunnelBlick (VPN access)
Google Notifier (Gmail alert)
and Facebook Notifications