WANBridge is a simple and easy to use WAN emalator. Simply insert a CD into a spare PC or server and boot it. It can also be virtualised, and performs reliably, allowing a custom WAN configurations to be set, including bandwidth, latency, packet drops and even QOS basic policies.
WanBridge is also free, head over to http://code.google.com/p/wanbridge/ to download it. There is also a quick quide to get you started. Highly recommended.