Google Chrome (Edge on Windows is not mature enough yet)
Google Earth – see the world
CCleaner – remove unnecessary files on Mac hard drive
Skype – communicate with audio / video with other devices
Teamviewer – remotely control other devices
MalwareBytes – scan and remove unwanted malware
VLC – VideoLan player – play most video / audio file formats
Dropbox – store and share files in the cloud
WinRAR – open most compression / archive file formats
8gadgetpack – use Windows gadgets on desktop