Here are some great software/applications/apps for mainly OSX/Apple/Mac, but there are often a Microsoft Windows or even a Linux version too. A list to keep up to date.

OSX

Audio and video

• Video Lan Client (VLC) – play, record, unicast, broadcast video and audio streams, listen to web radio
• X Lossless Decoder – convert formats like APE and FLAC to tagged MP3s
• Songbird – audioplayer
• Spotify – audioplayer
• FFmpegX – video conterter
• Handbrake – DVD ripper
• MusicBrainz Picard – tagger
• Tagr – tagger

Music

• Hydrogen Drum Machine – Drum machine
• DoggieBox – Drums
• Soundflower – Audio routing
• Audacity – Audio editing

Authoring

• TextWrangler – text
• Serna Free XML editor – XML editor
• LibreOffice – Office suite
• Apache OpenOffice – Office suite
• Scribus – desktop publishing
• Inkscape – illustrations

RSS-feeds

• Vienna – RSS feeds

FTP

• Cyberduck
• Filezilla

Communication

• Skype – audio and video
• Adium – im
• Pidgin – im

Others

• VirtualBox – create virtual environments for installaton of operating system
• Plex – server client home media sharing
• Chicken of the VNC – VNC client
• The Unarchiver – decompress files
• Blender – 3D composer
• Ccleaner – system maintenance
• Jomic – comic CBR reader
• Onyx – system mentenance
• SiteSucker – save a webpage locally
• WebArchiveExtractor – extract safari webarchives
• Ultracopier – advanced copying
• Wuala – cloud storage
• Diffmerge – compare files or folders
• Key remap for macbook – keyboard remapper (I use a windows keyboard)