Ever heard of Schmap? It's a publisher of online worldwide travel guides. I'll let them say more in their own words:

"The innovative technology behind Schmap Guides also lets end users publish their own ‘schmaps’ (to share trip itineraries, local reviews and more), and powers a popular range of Schmap Widgets, displaying maps with content and event schedules for travel, sports, concert tours and more on a fast-growing network of websites and blogs."

Cool, huh? Of course they have one for Amsterdam. Go exploring!