Most addictive games on the Net ?

I have addictions.

Lots of them.

All of them not at all healthy.

So, in order to feed one of the little terrors, namely The Game Germ, I would like to know if there is any games out there that truly fit the bill. My Number one game, for the past year is Heavy Weapon. So addicted was I that I even paid the tenner for it. (I noted the description when I went to the link just now, as calling it an 80's classic style game, so I am obviously reliving my teenage years again).

Ahem. Cough. Yes. Well.

It's the Bonus level I am addicted to more than the actual game itself as that was completed decades ago.

But really...what is everyone playing until their eyes are bleary red and their thumbs are dead ?

Feed me please;-)