Software that have found useful, mostly freeware or open source

Archive & File Handlers

7-Zip - Open source archiver
FileZilla - open source FTP
Free Download Manager - It is a powerful, easy-to-use and absolutely free download accelerator and manager
Crap Cleaner - Recuva - Defraggler -

Graphics

Paint.net - free image and photo editing software for computers that run windows

Games

Eve-Online - Steam Halo Maps HaloCE FTP

Office

Openoffice - is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more

Multimedia

Videolan - Free and Open Source cross-platform media player
Winamp - Free mp3 player
Jamendo - On Jamendo artists allow anyone to download and share their music. It's free, legal and unlimited

Music

A State of Trance
Trance around the World
Trance FM
Shoutcast Streaming Radio

System Utils

Tuneup Software - got it as a trial and got licence for £10 :)
SpeedFan - monitors fan and system temperatures
Nvidia Control Panel - allows me to change the graphics card fan speed, running winamp, 2 Eve clients got the GPU to 75C :(
Nod32 Anti Virus - saved me many times :)
Malwarebytes - malware scanner that has saved friends computers