I have lots of applications installed on my MacBook, but this is the list of software I’d install first and use most.
Chat with multi-protocol instant messaging. I really don’t need ten applications to do the job of one.
BBC iPlayer Desktop
Watch BBC TV online or offline in high quality. There’s no need to be a slave to the TV schedule.
Share or publish files. I use this for ease of sharing non-confidential files.
GIMP on OS X
Convert, edit, and retouch photos and scanned documents. This version includes some useful extras.
Print to any known printer. Uses the standard Apple CUPS interface but has more and better drivers than Apple.
Read and edit documents, spreadsheets and presentations. You can use this well as, or instead of, Microsoft Office.
Browse the Internet. I prefer this to Apple Safari.
Manage your email. I prefer this to Apple Mail.
Make video and voice calls. Not everyone has Apple FaceTime.
Protect yourself from malware with minimum fuss. Don’t pretend that Macs are invulnerable.
Talk on Twitter with a power-user’s Twitter client. This is my current favourite.