Assorted driftwood stranded from the internet...

Some of my favourite applets...

Experience modern art at its finest! This applet is (was) a part of Patrick Naughtons java demo library, and was originally devised by P. Haeberli (paint technique protected by US patent # 5,182,548).

Gomoku or five-in-a-row
In 1994, the dutch computer scientist Victor Allis proved that on a 15x15 board, the player who starts (black) always wins, a fact long known among professional players. Therefore a modified version of the game called Renju has been designed to even out this advantage, as well as prohibiting some moves.
Othello (or Reversi) on a hexagonal grid.
This is based on the "Iago" state evaluation function, which is simple to beat. Read the article by Michael Buro (a .ps.gz file) on the evolution of Othello playing computer programs.
Othello on the usual 8x8 grid
Nowadays the really good programs for Othello are almost impossible to beat, Logistello beat the world champion in 1997 and is considered one of the strongest programs ever written up to now. The ones above are fairly simple to beat, and even a below average player like myself regularly beat the reversi by com2us on my mobile phone.
Other java games
Whydoes a golfball have dimples?
An interactive GO tutorial
Online soduko