Postgres Enterprise Manager from EnterpriseDB is probably the most advanced you'll find. It includes all the features of pgAdmin, plus monitoring of your hosts and database servers, predictive reporting, alerting and a SQL Profiler.
http://www.enterprisedb.com/products-services-training/products/postgres-enterprise-manager
Ninja edit disclaimer/notice: it seems that this user is affiliated with EnterpriseDB, as the linked Postgres Enterprise Manager website contains a video of one Dave Page.