As far as I'm aware, MetaFilter users are pretty much ok with this way of supporting the site (they were actually asked before implementing this [1]). In fact,

As far as I'm aware, MetaFilter users are pretty much ok with this way of supporting the site (they were actually asked before implementing this [1]). In fact, it was frowned upon posting affiliate links with users' codes. [1] http://metatalk.metafilter.com/11174/Im-proposing-a-small-change-to-amazon-URLs http://metatalk.metafilter.com/11174/Im-proposing-a-small-ch...