Hidden sites and game passwords -I do not suggest that anyone do Jhudora's quest or Illusen's quests because the items you have to find cost much more than the prize you will reiceve.
http://images.neopets.com/games/g153_v1.swf Advent Caledar (gives a prize to anyone who visits this site every month in Decemeber): http://www.neopets.com/winter/adventcalendar.phtml
Jelly Blobs of Doom (this is a hidden game, to get extra points pick up the negg that appears): type "rainbownegg" http://www.neopets.com/gamescores.phtml?game_id=359
Matching Madness (unlisted game)
http://images.neopets.com/games/g150_v1.swf Kiko Match Version 1 (unlisted game)