Games
Americas Army - Tactical shooter
F.E.A.R. Combat - 1st person shooter
Wolfenstein: Enemy Territory - 1st person shooter
Frets on Fire - Music Game
Emulators
VICE - C64, C128, VIC20, all the PET models, PLUS4 and CBM-II emulator
DOSBox - DOS- emulator
WinUAE - Amiga emulator (You will also need kick.rom which is not for free)
Scumm VM - Open Source game engine for LucasArts games
Nestopia - NES emulator
Project64 - Nintendo 64 emulator
Fusion - Multi system SEGA emulator
You will find all these emulators and a LOT more of them on www.emulator-zone.com
Here's a few abandonware game webpages:
Security
AVG Anti-Virus Free Edition - Free Anti-Virus Software
Avira AntiVir Personal Edition Classic - Free Anti-Virus Software
Sygate Personal Firewall - Free, easy to use Firewall
Spywareblaster - Anti Spyware and Adware program
Ad-Aware Free - Detection and removal of Adware and Spyware
KeePass Password Safe - Excellent Password Management Software
Recuva - File Recovery
Maintenance
CCleaner - Registry Cleaner
RegSeeker - Registry Cleaner
UltraDefrag - Disk Defragmenter
Defraggler - Disk Defragmenter
Media Players & Codecs
Foobar2000 - Audio Player
Aimp2 - Another excellent Audio Player.
Winamp - Audio & Video Player
VLCplayer - Video Player
KMPlayer - An excellent media player with built in codecs.
Media Player Classic - Home Cinema - One of the best media players there is.
BSplayer Free - Older version with no adware but still an excellent software.
K-lite codec pack - In my opinion, the best available codec pack there is. With Media Player Classic.
Find other codecs & codec packs on www.free-codecs.com.
Others
CDBurnerXP - Burn CDs and DVDs for free!
Firefox - The best web browser there is!
Thunderbird - The best Email application there is!
OpenOffice - A freeware Office Suite.
Skype - Call your friends for free with Skype.
TeamViewer - Remote Desktop Sharing - Remote Access
Google Earth - A map of the entire planet!
Izarc - Freeware archive utility.
FileZilla - A free FTP client and server.