So what is this? It's a list of all the online games I will find. It's more for my benefit than anything else - so I won't have to go and dig through my bookmarks every time - but it could be interesting for other people as well, I think.
To play these games, you will need Java enabled or Shockwave and/or Flash installed (depending on the game).
Basically, multiplayer tetris. You have to download the tetrinet program and play with your friends - one person has to act as a server, and give out the IP to the other players. The list of rules and everything else you need to know how to play is in the readme.
You have to remove the required number of blocks to advance to the next level. You get bonus points if you clear more blocks than the required amount. Hint: drop blocks on the top and on the left first. The less blocks move when you drop blocks, the better.
The players take turns at drawing a random word (that the game gives you), and the others have to guess the word. You get points for correct guesses and bonuses for time. Whoever has the highest score at the end of the game wins. Very fun if you play with friends.
The aim is to clear the board before time runs out. Start by clicking any two matching symbols next to each other. Look for other matching symbols that are along the outside of the grid. If you select two that cannot be connected, they will not disappear. Only straight lines with 2 or fewer right angles can connect the symbols, so diagonals won't disappear unless you have cleared a straight-line path between them.
You have to trace with your mouse the outline of a bunny. It's harder than it looks - especially since the game is very picky. You only need to stray by one pixel from the outline, and you lose. Do not attempt if you have no patience.
You have a screen full of apples. Click on two apples to swap them (they must be next to each other, horizontally or vertically). Each swap must make a matching set of three apples lined up vertically or horizontally. You get extra points for longer matches or for additional matches resulting from a move. The game ends when you run out of matches. You can use the Hint button but you will lose 20 points. Also, you lose a point for every 5 seconds spent thinking!