Pokemon HeartGold Cheats

Unlockable Pokewalker Maps
There are over 20 Pokewalker maps currently available to anyone and everyone who owns them. The trick is obtaining Watts and getting the National Dex. Note that some of the following are event-only, so the Yellow Forest (for example), is unattainable right now.

Beautiful Beach: Obtain 200 Watts
Beyond the Sea: Obtain a foreign pokemon via use of the GTS
Big Forest: Obtain 40,000 Watts and own the National Dex
Blue Lake: Obtain 2,000 Watts
Dim Cave: Obtain 1,000 Watts
Hoenn Field: Obtain 5,000 Watts and own the National Dex
Icy Mountain Rd.: Obtain 30,000 Watts and own the National Dex
Night Sky's Edge: Trade a fateful-encounter Jirachi onto your HG or SS
Noisy Forest: Available from the start
Quiet Cave: Obtain 100,000 Watts and own the National Dex
Rally: Wifi Event from January 29th to February 28th, 2010 (Japan)
Refreshing Field: Available from the start
Resort: Obtain 80,000 Watts and own the National Dex
Rugged Road: Obtain 50 Watts
Scary Cave: Obtain 20,000 Watts and own the National Dex
Sightseeing: Wifi Event from November 14th (2009) to to January 11th (2010) in Japan and from April 17th to May 31st, 2010 in Korea
Sinnoh Field: Obtain 25,000 Watts and own the National Dex
Stormy Beach: Obtain 65,000 Watts and own the National Dex
Suburban Area: Obtain 500 Watts
Town Outskirts: Obtain 3,000 Watts
Tree House: Obtain 15,000 Watts and own the National Dex
Volcano Path: Obtain 10,000 Watts and own the National Dex
Warm Beach: Obtain 7,500 Watts and own the National Dex
White Lake: Obtain 50,000 Watts and own the National Dex
Winner's Path: Wifi Event from May 6th to June 25th, 2010
Yellow Forest: Wifi Event from April 1st to May 5th, 2010