You need to include some numbers in the /1/2/3/ part of the call, but it can be whatever you want. Use it for version control or for dating the implementation. For instance:
http://thumbnail.shopwiki.com/i/data/WidthxHeight/5/3/2007/ - using the date this article was written
To use our service you must include a "Thumbnails powered by ShopWiki" link at the bottom of the page.
The link should say "Thumbnails powered by ShopWiki" and link to http://shopwiki.com/w/thumbnail (this page) like this: