ThirstyAffiliates is a suite of affiliate marketing tools that helps the average WordPress blog owner monetize their content with powerful efficiency.
Not only can you turn those ugly affiliate link URLs into pretty links that use your website URL, but you can also extend this functionality with other amazing features like automatic keyword linking, stats, handy importing tools, geolocated links and other great add-ons.
This plugin is FREE but you have some paid addons:
Autolinker: $49 – Automatically link up keywords to affiliate links throughout your blog.
Geolocations: $49 – Geo-target visitors with country specific affiliate links.