It's always been difficult to link to Amazon, because you have to find the ASIN (product code) to put in the URL. To avoid this, the OpenAm service lets anyone link directly to Amazon product pages, just by using the title (and the author if the title's not precise enough).
For example, to link to Stephen Wolfram's 'A New Kind Of Science', you can use the URL
(the %20 is the encoding for a space).
To link to Howard Rheingold's 'Smart Mobs', you could use
and to link to 'The Life Of Pi' using your associates ID (to get sales commission), just use
If that's still too complicated, you can use this OpenAm bookmarklet to generate the links automatically.