Created new topic, but posting here also:
Saw this yesterday so thought I'd post it. I hadn't heard of it before, but ERT is a 2003 naval battle sim based around a fictional version of WW2. More info on it here:
[url=http://en.wikipedia.org/wiki/Enigma:_Rising_Tide]http://en.wikipedia.org/wiki/Enigma:_Rising_Tide[/url]
It's got good ratings on various sites (including 75% from PC Gamer) so worth a download. The original game also had Starforce protection but this release is DRM free. I burned the ISO to a DVD and installed it that way, but I think extracting it with WinRar or 7-zip and installing from the folder will be fine because it doesn't require a CD in drive.
Without further ado, link to download can be found here, provided by one of the game's developers:
http://www.subsim.com/radioroom/showthread.php?t=156626
Disclaimer: the developer has released it but I'm personally uncertain whether they are fully allowed to do so? Maybe they have full publishing rights or they've reverted back to them or something.
Via:
http://www.rockpapershotgun.com/2009/10/04/enigma-rising-rip-tide/

I think this one has not been listed yet: Danger from the deep, an Open Source World War II german submarine simulator

Have you been through this list?

Pardus
MMORPG.
Browser-based.
Sci-fi 2D tile-based gameplay.
Free to play, but account required (one account per person. each account can play 2 free universes with one character in each).
Premium available for ~US$3 per month on several payment levels (1 month, 3 months, 6 months, 12 months) - no massive bonuses for this, but you do get the option of making a 3rd character in the premium-only universe/server
(mostly) classy community
average to steep learning-curve, but there are lots of people to help you out (my alliance, for example, is dedicated to providing help to newer players above what is taught in the small tutorial)
It's mostly based as an homage on the old 8-bit computer game, Elite, but has changed quite a lot of things.
My Profile in Pardus <-- Warning! Has been known to cause blindness!!

What about Supaplex - http://www.elmerproductions.com/sp/
A very nice puzzle, it only runs in DOSbox though..

http://www.greydogsoftware.com/home.php
Total Extreme Wrestling 2005
Wrestling booking simulator, released for free to advertise later versions of the game. Quite an involving strategy game, if you can look past the clunky interface.

Arx Fatalis Balance and Enchant Mod!.

updated with your sugestions and lots of another games XD

strange nobody mentioned TAGAP yet.
http://www.tagap.net/

Damn you! Beat me to it. Oh well...I'll just recommend Kumagames, a site filled with over 150 free episodic games. WARNING: They play like average games, so don't expect AAA title quality.

neopets for flash games lol

"Good" is a meaningless term. One persons trash is another's treasure. That being said, I would like to suggest two of my favorites:

Dwarf Fortress [url=]http://www.bay12games.com/dwarves/[/url]
Incursion [url=]http://www.incursion-roguelike.net[/url]/
:)

There are tons of free mods for BG I & BG II!
Just check these links:
http://iem.rp-addict.com/index.php
http://www.spellholdstudios.net/
http://elsalondelosespejos.iespana.es/MBG2.htm
Baldur's Gate Trilogy and BGW are simply awesome!

mod for hl2, sdk required:
dystopia: [url=]www.dystopia-game.com[/url]

It looks like a whole load of free standalone games are going to be added to the list thanks to the Unreal Development Kit being made freely available.