Qlab

Show controll software for MacOS. Multi channel audio and video support. Basic version is free and rental licenses are available.

Screen Monkey

Media server with pixel mapping at a sensible price! It may not be a hippo but it certainly works.

MagicQ

Profesional lighting controll starting at £10!

Sound Exchange

Need to batch process some audio files? Try this little freebie.

Foobar2000

Freeware audio player which is also portable (you can run it off of a pendrive.)

Pendrive Apps

Fantastic collection of portable software.

VLC Player

Video Playback without bloat. Supports more codecs than Windows Media Player.

AVD Multiplay

Audio Cue software. It works, it's free and pretty well supported too.

Ableton Live

There is so much this software can do although I have to confess I've probably only used about 10% of it. Last time I used live it was to create effects loops for my desks USB connection... afterall Lag is just pre delay.