This is a FULL list of the areas in MegaMan Battle Network 2.

Megaman Battle Network 2
Area Modifier
82000dc4 XXXX
-------------
0:ACDC Metroline
1:Marine Harbor Metroline
2:Okuden Camp Entry
3:Den Airport
4:Net Airport
5:Netopia Park
6:Crew Room
7:Kotobuki
8:Penthouse
--------------------------------
Network Modifier
-------------
0090:Den area 1
0190:Den area 2
0290:Den area 3
0390:Den Square Ent.
0490:Den Square
0590:Den Board Room
0091:Koto area
0191:Under Koto
0291:Koto Square Ent.
0391:Koto square
0491:Koto Square 2
0591:Gospel HQ
0092:Yumland 1
0192:Yumland 2
0292:Yum Sqr. Ent.
0392:Yumland Square
0492:Treasure Room
0093:Netopia 1
0193:Netopia 2
0293:Netopia 3
0393:Netopia Sqr. Ent.
0493:Netopia square
0094:Undernet 1
0194:Undernet 2
0294:Undernet 3
0394:Undernet 4
0494:Undernet 5
0594:Undernet 6
0694:Undernet 7
0794:WWW area 1
0894:WWW area 2
0994:WWW area 3
0A94:Undernet Sqr. Ent
0B94:Undernet Square
0C94:UnderBoard
-----------------------
Houses
-------------
2:Lan's House
3:Lan's Room
4:Mayl's House
5:Mayl's Room
6:Dex's Room
7:Yai's Room
8:Yai's Bath
A:Yai's Hall
------------
Buildings
-------------
0102:Scilab Lobby
0104:Test Room (not the kind you're thinkning of)
0106:Fake Message? (Crashes)
0107:Mother Comp. Room
0205:Okuden Dam
0103:Boarding
0203:Airport St.
0205:Underground
0305:Hotel Room
0405:Jewelry Shop
0505:Net Castle
0605:Banquet Room
0705:Trap Room
0406:Cock Pit
0107:Koto Apartment 1F
0B07:Koto Apartment 30F
0108:Last Room (Final Boss)
---------------------------
Comps
-------------
0080:Gas Comp.
0081:Bomb Comp.
0082:Mother Comp.
0083:Castle Comp.
0084:Air Comp.
0085:Apartment Comp.
0585:Gosp. Server
-----------------

-Press start, enter any folder and exit. Viola! You are in that area now! Enjoy!