An excellent guide to Amsterdam coffeeshops.
Several editions of this guide have served as my bible
over many visits.
The 6th edition covers Kip's top 40 coffeeshops.
There are several other coffeeshop guides on the web.
Like the books, English language sites tend to be by Brits and Americans
living in Amsterdam. For that reason they will have more first-hand knowledge
of the scene than an occasional visitor like myself.
Strangely, though, none of these sites has a map.
You may, therefore, wish to use the map here in conjunction with
the reviews on these pages.
Midnight Express
Cheap coach trips from the UK to Amsterdam specifically for smokers.
I've always flown there (and flown back) myself
so I don't know what they're like, but it sounds like fun!