Helsinki now has a large and well-established Design District and the city was designated as the World Design Capital for 2012. There is an excellent pocket-sized map of the District available in English. Well, it starts out as pocket sized but unfolds and unfolds and unfolds to show an area more than 10 city blocks by 10 blocks fanning out, mainly to the west and north of the Design Museum.
Each shop or service is numbered and there are separate groups for interior and design, clothing, antiques and art, jewellery, galleries and museums, food drink and hotels and finally services ... all coded by colour.
If trying to cover this large area and the 200 or more businesses that make up the District seems daunting then remember that in Finland coffee and cakes are much appreciated so there are plenty of places to have a break as you search the shops and galleries. In fact one place that I will certainly seek out is LoKaL which describes itself as 72% art 28% coffee so it sounds exactly my kind of place.