I wish I had this a few years ago:
BGPmon can monitor your prefixes and alert you in case of a ‘interesting’ path change. Recently this has received quite some attention. Specifically after the Youtube hijack and the demo given at defcon. Path changes can be of different kinds, such as more specifics, change of aspath, change of origin AS, Transit AS or any combination of this. BGPmon classifies these changes in types. This software was written over the course of 1.5 years, mainly for private use. However given the more widespread interest I decided to make it available everyone interested.
This tool is a nice addition to any enterprise using BGP.