Probably the best single online game you can find, but still unbelievably **** (replace stars as you see fit).
Basically the concept is simple, it's a space-war game where you attack people with ships. You are a planet, you mine, you build ships, you send them to attack and defend others. It used to be such an exciting pass time but has grown duller and duller, and now the only way we know how to have fun playing it is to cheat. So is suggest this. Most people who don't have a life and take this game too seriously will say that politics is a very important part of the game, that you have to be in a good alliance and that you have to be on IRC (Internet Relay Chat) four hours every day making friends and spreading the love. This is all lies. Just cheat and you'll go far. Or at least.. further than Gareth.

:: Empirequest ::
It's a cheap Planetarion clone that is finally closing down because it literally is too cheap. Thank god.
Update: It didn't shut down, but is still crap.

:: Jippii Online Games ::
I can proudly say I discovered this beauty that has sadly been surpassed. It's the way modern life is these days, the best become good and then gradually fade away into nothingness with nothing to remember them but some text on a free website run by those who were once honoured to use it's services. Jippii is mainly a two player gaming kingdom, you play verses another person in a variety of classic and new games on a chat-room / game interface. The games include Minigolf, Pool, Chess, Battleships and Cannons. You can also play single player games if you don't have any friends like Minigolf featuring lot's of different courses, and the originally named 'Bomb Game'. For a few months it was the talk of the town and holds a place in all our hearts.

:: Shockwave ::
Not just a gaming website but also a script in it's own right. It will feature the best looking games you'll find online, very smooth and colourful, and all types from action adventure, roleplaying, racing, quizzes, puzzle and everything you could imagine. Except Minigolf. Well worth checking out if you have time, and you must have if you're wasting it reading this. Plug-ins needed.

:: Coffee Break Arcade ::
Free games for everyone indeed, Classic Games, Shooting Games, Racing Games, Cool Games, Classic Games and Casino Games. Alot of supposed comedy is hidden in this particular nest with such games as 'Bounce Out', 'Save Them Goldfish!', 'Udder Insanity' and 'Cutie Quake'. Alot of the games are visually similar to ones you might find at Shockwave.com but are all very Coffee Break Arcade styled. Designed for bored employees stranded at work, it has evolved into a quality establishment home to the very best of free online games you'll find about. I personally recommend 'Snowcraft' in which you have a snow ball fight against an ever increasing number of snow-weilding opponents. The Robe is partial to a bit of goldfish saving and a Skateboarding game in which it's possible to do a double backflip whilst idling along a flat street.

If you're interested in sampling any of these gems, use the bar on the left for linkage to each site.