I recompiled and updated list for you, maybe you can make this sticky thread for yourself to refer.
Guides:Avatar Guide:
http://www.neopets.com/~The_Pet_EaterJellyneo:
http://www.jellyneo.net/index.phpIn-Depth Battlepedia Guide:
http://idb.finalhit.org/Monthly Free Gifts:http://www.neopets.com/freebies/Daily Free Stuff:http://neopets.com/bank.phtmlhttp://www.neopets.com/island/tombola.phtmlhttp://www.neopets.com/desert/shrine.phtmlhttp://www.neopets.com/desert/fruitmachine.phtmlhttp://www.neopets.com/worlds/geraptiku/tomb.phtmlEvery pet you got can go fishing once per 12 hours (so 3 pets = 3 tries)
http://www.neopets.com/water/fishing.phtmlOnce time per day
http://www.neopets.com/jelly/jelly.phtmlhttp://www.neopets.com/prehistoric/omelette.phtmlEvery 20 mins:
http://www.neopets.com/faerieland/springs.phtmlDaily Tries:Daily Puzzle
http://www.neopets.com/index.phtmlLunar Calendar
http://www.neopets.com/shenkuu/lunar/Faerie Wheel
http://www.neopets.com/faerieland/wheel.phtmlFor 100 NP, you stand to win more than 6 million NPs legally!
http://www.neopets.com/halloween/strtest/index.phtmlhttp://www.neopets.com/winter/snowager.phtmlHours the Snowager is asleep daily:
6:00am - 7:00am NST
2:00pm - 3:00pm NST
10:00pm - 11:00pm NST
http://www.neopets.com/medieval/turmaculus.phtml - Dangerous, can eat ur petpet if so suay!
http://www.neopets.com/medieval/symolhole.phtmlhttp://www.neopets.com/medieval/guessmarrow.phtmlMeteor's Free Gifts - Space food, weapons or maybe nothing at all.
Hourly Tries
http://www.neopets.com/moon/meteor.phtmlHidden and unusual places:http://www.neopets.com/jelly/ - Jelly World is not in the map in case you don't know.
When you go to see New Features in neopets you wont get to see Jelly World news as they are hidden as well.
To view the news for yourself, go to New Features and rightclick on the page. Hit 'View Source'. Search for 'jelly'. The first thing you find should be it!
The Gypsy Camp
http://www.neopets.com/halloween/hwp/gypsy_camp.phtmlNeovia the Cursed Town
http://www.neopets.com/halloween/neovia.phtml?For spending your millions of NPs
http://www.neopets.com/faerieland/hiddentower938.phtmlwhen You complete Lab Map, you get access to lab to zap your pet!
http://www.neopets.com/lab.phtmlhttp://www.neopets.com/worlds/deadlydice.phtml - around sg time 3pm to 4pm Dracula awakes, forgot the real timing, but neopet timing should be midnight time. 12.00 am. Play dice with Dracula to win or lose a level...once I play 4 times draw games with him and won 8 free levels in the end plus free avatar
Go there when you completed a Rainbow Faerie Quest!
http://www.neopets.com/faerieland/rainbowfountain.phtmlCan go try and crack your brains for the ultimate hardest to find avatar
http://www.neopets.com/shenkuu/cooking.phtmlNeopet Magazine Word Scramble:http://www.neopets.com/wordscramble/wordscramble.phtmlNew Sponser Games:http://www.neopets.com/games/play.phtml?game_id=869http://www.neopets.com/games/play.phtml?game_id=870http://www.neopets.com/games/play.phtml?game_id=683Altador Cup!http://www.neopets.com/altador/colosseum/index.phtml