Heya!
This is just a quick Checklist to keep track of which Shops you already visited for the "SHOPPING!!!!" Achievement.

Electric Town Plaza:

AKW Cafe [ ]
5Days [ ]

Radio Kaikan Area:

NEWNEYS [ ]
Gamers [ ]
Art Stop [ ]
Yamada Denki [ ]
TOKIWAMUSEN [ ]
maidreamin [ ]

Main Street NE:

sofmap Hon-kan [ ]
Toranoana Akihabara Store A [ ]
animate Hon-kan [ ]
LAMMTARRA EPIXIS AKIBA [ ]
Hon Quixote [ ]

Main Street NW:

Akiba*sofmap No.1 Store [ ]
TRADER Main Store [ ]

Main Street SE:

Suit Store [ ]
LAMMTARRA Akihabara Store [ ]
Granvania [ ]
MEDIALAND [ ]

Main Street SW:

GO!GO!CURRY Akihabara Chuo-dori Store [ ]
Mulan AKIBA Chuo-dori [ ]
sofmap Amusement-kan [ ]

Side Streets:

K-BOOKS [ ]
superpotato [ ]
KOTOBUKIYA [ ]
akibaoo No.2 Store [ ]
TSUKUMO Personal Computer Main Store [ ]
TSUKUMO Personal Computer Main Store III [ ]
TSUKUMO Personal Computer Main Store II [ ]

Junk Street:

akibaoo No.5 Store [ ]
DOSPARA Akihabara Main Store [ ]
DENSETSU NO SUTADON [ ]
march-rabbit [ ]

Yodobashi Area:

YODOBASHI AKIBA [ ]

Akihabara Park:
Go!GO!CURRY Akihabara No.1 Store [ ]
JANPARA Akihabara No.4 Store [ ]
PINAFORE [ ]
SHOSEN book-tower [ ]