Pricepeek - Compare prices of the same product across all Amazon locales
Domcomp - No-nonsense domain price comparisons, updated daily
The Mac Index - Compare Apple product prices in different countries
Waatcher - Automatically buy on Amazon at your target price
Mac Buyer's Guide - Recommendation on when to buy Apple products
dofo.com - Domain search platform Dofo.com gathers all registered (350 million) domains of the world in a single place. Dofo also brings together all the domain names that are on sale, provides useful features, all completely free.